say something if it bothers you. You most likely will get backlash but who cares. I personally find the gentleman resting his legs far less offensive than the lady who plops her feet directly on the table. Gross.
I can't tell you how many times I have told loud Americans to lower their damn voices here in Europe (particularly college-aged women but also loud businessmen in lounges) because they are so clueless and annoying as hell...