I think I agree that ANYone who posts here is likely to get a dose of aggravation, and builders would be likely to get more. That's not a good thing, and it's the main thing I don't like about this forum. I do think, however, that responding to Don's lug thread with pics of other lugged frames you like is completely appropriate, unless you're doing it just to wind him up. I've posted pics on one of these threads before, with no intention to cause upset, and been castigated. I've also seen Don be pretty, uh, direct with people in other threads who weren't being annoying.
I think it's six and two threes here. You can't expect to come to a discussion forum, and dictate what will be posted in your thread. We come to this forum to talk about bikes, not to be lectured about bikes. I respect Don's desire to promote his show, and other people's work, but doing that in a structured way, with nobody interrupting is just not what this medium is for. Don's reactions to people doing what is, in fact, entirely appropriate, that is to say replying with on topic posts and pictures (of pretty lugs) to a thread entitled "Lug shot of the day" is what has won him some, shall we say, enemies. Now, those people are being idiots, for sure, and should quit it, but let's not pretend that there's not a bit of fault the other way too. Don is, genuinely, demanding (rather than asking) something that's a bit unreasonable, and is far from the most polite or politic person to ever post here.