From the original post, it doesn't sound like the three of you have played together; you've just seen the two of them together (once?). I wouldn't necessarily rule out joining them based on that. If they've only just started playing with each other, perhaps the new guy was still finding his role in the act and, over time he'll get less busy. Perhaps he feels the need to fill some space, and with a bass player added he wouldn't.
I'd say it would be worth asking for a rehearsal session with the two of them to see how it goes. If he's still overplaying in that context, it's your opportunity to raise it constructively. If your friend doesn't agree, that's where you can bow out gracefully.
I'd say it would be worth asking for a rehearsal session with the two of them to see how it goes. If he's still overplaying in that context, it's your opportunity to raise it constructively. If your friend doesn't agree, that's where you can bow out gracefully.

