He needs a girlfriend or a couple of cases of beer or some other college diversions. "Hmmm, it's Tuesday night so I'll go hang @ the library after 10:00 and not have my ID". It's not like the less well-armed library folks didn't first ask to check his id and then, when he told them to buzz off, they decided to call the cops. Or, most likely, they checked w/ their boss who looked it up in the manual and decided 'oh well, another one of these douchebags, not my problem, I'll have to call the damn police and write a stupid report up about the whole thing. There goes my exploration of Fantasy Baseball Café tonight. Argh'. Then, 20 min later, the 5-0 roll up and he's still hanging out and causing a ruckus, interfering w/ the other college students trying to do their homework or find the recipe for LSD or making out whatever else they are doing in the library then and they try to get him out and he continues to refuse. What a dumbass!!
When I was in college, we were playing soccer in the street w/ a bowling ball wrapped in newspaper that we'd set ablaze w/ lamp oil and a cop drove by and we said 'we've got it under control officer' in a respectful manner (even though we were 18 sheets to the wind...) and he was like 'ok' and drove off.
Fighting w/ cops generally means 1) you are going to lose, at worst, the cops will keep calling more cops until they take you down, cf. Rodney King riots, et al and 2) the cops are going to have to do some paperwork, which likely means a 'loss' as opposed to driving around in the squad car as far as the cops are concerned but still beats being tasered and immortalized in a silly YouTube video.