Hey Mike,
How are ya? Interesting thread. I think you did make the right choice here. For me, the issue is not so much your being asked to appear topless. In this case, I tend to agree with Mark, and think they were probably looking (particularly considering it was a music video) for guys who were prepared to get their pecs out, look ripped etc. and that it was a relatively innocent request - dancers, for instance, do this kind of thing all the time, and, in point of fact, I was appearing in a production with a couple of guys who did this just recently - and I don't think it ever became an issue. As people have said, there is a qualitative difference between men and women going 'topless' and, in fact, men in the industry so often go topless (particularly in e.g. dance circles, circus or in physical theatre) that we barely register the fact that they are actually doing so. For women, going topless is a very different issue - because it is almost always used to designate something different about women than it is about men.
With all this said, though, I think you were right because of the principle of being allowed to know about this requirement *before* the audition. There are a whole number of reasons why this should be the case:
1. As has been said, it reflects badly on the outfit that they are not prepared to give you all the details of a project until a very late stage in your application for it - it suggests strongly that there is something dishonest about their whole setup, and there is no good reason why they shouldn't have mentioned this fact if they knew all along it was going to be a vital requirement.
2. There is the possibility that had you known of the commitment beforehand you might not have followed through on the application - and that *should* be your choice as an actor. Clearly, they may have been worried that they wouldn't get as many applicants if they were upfront to start with...but if all the applicants will simply turn them down at a later, rather than earlier, stage, then they haven't been helping themselves by being secretive.
3. Questioning your agents' attitude is perfectly reasonable - regardless of whether you feel the request is degrading, surprising, unnecessary etc. or whether you actually feel 'why the hell not?', it may be of concern to you as to whether doing the project will send out the right impression of you vis-a-vis your agent. At the very least, you should be entitled to spend a little time discussing it with them, on the basis that the fact that you needed to go topless hadn't been revealed at any earlier stage in the process. Not to allow you the option of discussing the question and then coming back to them over it again smacks of amateurishness on their part.
I have always said that being nude (in whatever capacity) is very much a personal choice for the actor. I tend to think that there is nothing to be ashamed of, and we should be confident enough in who we are to display our bodies if needed, but I also appreciate that there is a lot of exploitation in this industry, that women 95% of the time are placed in more difficult positions than men, and that everyone has different limits. Nor do I think that being perpared to do 'nude scenes' or otherwise makes you a better or worse actor (as some like to claim!). All I can say is that, having done a variety of topless scenes, full frontal nudity etc. myself, I am always surprised that, whenever the interest is not primarily to titillate, no-one actually seems remotely bothered by the nudity, and it is just accepted as part of the piece. It is, perhaps, more demanding to be filmed nude or topless than to appear so on stage, because the record will always remain, but there is little distinction in real terms.
Still, in this case, I think the real issue remains that you weren't told. You should have been given all the info needed, and this would have resolved all the problems - whether you needed to discuss with your agent, whether the request put you off, whether you felt you needed to get yourself to the gym in preparation etc. etc. Not telling you reflects badly on them, and is no reflection on you. You took a stand, and you were right to do so.