While it appears rude, I think it's just saying the team members and progress already were enough to provide for the mod, you were going to be nothing more than an extra. He knows your qualified, you're just not "needed". It's nothing rude or disrespectful there at all, he wasn't depending the whole mod on you. While that's a nice paraphrasing of the converstation, I've yet to see any real logs of the guy doing much disrespect.
I think DaveL is funny, I spoke to him once or twice on IRC, he has all rights to command the modification to whatever his likings are, it's his project and everyone has the choice to contribute or not. It's his project, his ideas and his choice how to treat people, this is just one case of a crybaby.