I am fine with guys standing beside the road dressed as a devil or a chicken or whatever they want, and fine with them running beside the road. The problem is when they are either trying to interfere with riders (like with Nys) or just so stupid that they do it by mistake (like with Guerini) or do it in the thought that they are helping. Having ridden a lot of famous climbs while the fans where there I can tell you that it does make for a great atmosphere if they are keeping their distance, but is scary when they get too close.
People say we should put police there, but police only enforce the rules that society makes. Peer pressure is what it is all about, whether legalised or not. The only way we can solve it is to let the idiots know that it isn't acceptable, and this is much easier for the people on the side of the road (who have time and energy) to do than for the poor guys trying to race. I'm not saying we should start vigilante groups and start hanging or shooting people, but if you think it is wrong then you should say so, to the people doing it. If other people around you join in with telling them it is wrong, then it probably is and they will now know it and will think twice before doing it again. If the people around you side with him, then maybe you need to adjust your standards. That is how societies work.
Personally, I hate people coming out of a crowd to push me. When you are struggling to keep the pedals turning and your momentum going up the hill the absolute last thing you want is some idiot running out of the crowd and pushing you sideways, and I confess to having shouted abuse at people doing this to me (sorry to that kid on Col de Saisies in 2009, I didn't realise how young you were or I wouldn't have used those words...). On the other hand, at last year's Vuelta there were some killer final climbs, and I reckon a couple of people would have had to get off and walk if they hadn't been pushed...