You'd probably be amazed at how many potential clients "discriminate" against me because they are looking for a bottom, or for someone older, or taller, or hairier, or larger, or white, or black, or less expensive... Yet, I would encourage them too, because, just as I won't waste their time if I don't think it is a good match, I don't think they should either. That said, I have never refused to meet a client because of his age. That is fake news!
PS - I very much do already have a weight limit for particular activities. But it is fair to say that I might see it as I am too light for what he is looking for, rather than that he is too heavy.