I think the the most telling thing you said was "This wasn't the first problem we'd had with him in this regard." The problem is that you don't trust him, not that he was late. I wouldn't let someone go because they missed a rehearsal, I would if I felt I couldn't rely them. It is not fair to anyone. All of us who have done this for any length of time have had to live with our casting errors, or take deep breath and make decision to let someone go. I am impressed when people do what they say they are going to do.  I would much rather work with someone who will be on time, learn their lines, be at rehearsal to rehearse and be part of the team. I can do far more with that type of performer then with someone who may be more talented or have more experience, but is a loose cannon. We are asked all the time why directors go with a known performer. This is why. I really like a certain percentage of the known factor to be part of the cast. Anyway, I have my own little casting error to deal with right now. Lovely girl. No one, including her, have any idea what she is going to do or say next. I am now completely gray!

Well, we're not very quick with ax. This is the first time I've been involved with anything like this. As far as the director being responsible for doing the dirty work, he was planning to but I jumped in and took over as he was somewhat of a "guest" director for us. He did wind up communicating with the actor about the issue. As for wanting to change casting decisions, there was none of that, he was doing fine. As for absenteeism in other shows, we had no knowledge of that and I'm not sure how we would, no one now in our community theater had any experience with him. I suppose we could start asking for phone numbers of directors of shows auditionees have been in before and call them before casting. Is that actually something people do? And going off on a tangent here, this is why directors tend to cast people they know and groups get the reputation of being snobbish.
And as to when the problem happened earlier, it was discussed with him. But in thinking about it, I'm not sure we forfeit the right to deal with the situation even if it hadn't. In my book there's a big difference between blowing off a reherasal with three weeks to go and with three days to go.

Last year I fired an actor just 3 weeks before opening. He had been unhappy about the small role I gave him from day one. The play was The Curious Savage and he was perfect for the judge, but he wanted to be a star. He is not the best actor in town but he had done well for me before (when he had a bigger role). So from the beginning, he either came late, or called and said he couldn't make rehearsal. I had told him that I needed him there. And they are given their rehearsal schedule 8 months ahead of time (we only do one play a year in a senior community so they get scripts and rehearsal schedule before they go north for the summer). I felt there was no excuse for him to schedule other things on a rehearsal date and I knew him well enough that he was trying to punish the cast for having such a small role. When the last straw came, I let him go. With no notice, I asked the sound man to do the part and he did a great job. 

One of the few times in the 18 years I've been directing shows that I had to fire someone was during FOREVER PLAID. We had a guy who was a good singer, a good actor, but who I had worked with before and he ALWAYS thought he was God's gift to whatever production he ever worked on. I did Sweeney Todd with this guy once and he was ANTHONY in that show....talk about FUNNY STILTED OVERACTING like you've never seen.  His delivery sounded like a computer generated voice. Hilarioius.  Anyway, for PLAID, he didn't read music - something he never indicated.  All he wanted to do was to learn it by rote - something I don't have a problem with but he couldn't even recognize the notes by name.  So if I said to him to sing an A in a four part thing - he didn't even now where that was - yet he was a guitar player, a piano wanna-be player and a singer - but had NO clue as to CDEFGABC or anywhere in the mix.  He became very vetchy about EVERYTHING and since I was music director as well - I finally had to tell him to take a hike - and will NEVER work with him again.

I am directing Peter Pan and the cast has been told under no uncertain terms that they must all be present at tech week. There is one exception of an actor that wrote on her audition form of a conflict hence we were aware of the conflict when we cast her. This is an extremely tech heavy show with the flying etc, so it is imperative they be there. One of my leads wants to celebrate his birthday in NYC during tech, I told him it was his choice but I would recast him if he didn't show. It will break my heart, cause he is a great kid, but I am adamant that they be there and this is what they signed on for when they signed their contracts. Some may consider it harsh, but I feel that it is the best for the cast and crew.