Numerous second chances? I'm aware of one other incident - that isnt' exactly numerous.
If he knew in advance they were going to rob someone, he should be gone. But it's certainly within the realm of possibility he didn't. People, especially people stupid enough to commit a felony, sometimes do things without a lot of forethought or premeditation; I'm going to go out on a limb here and guess that neither Edwards nor Richardson has ever held anyone up before or they wouldn't have been on the team in the first place, so there's a very significant chance Janzen had no earthly idea what was going to transpire, until it was already transpiring, and at that point it was decidedly too late for him to do anything about it.
I would venture that a very high percentage of the posters on here calling for him to be dismissed, have themselves done something at least as stupid as drinking underage, or having pot, or whatever he did on the strip that got him the one-game suspension, at some point in their lives. If Janzen was in on the robbery, boot him; if he had no idea the other two were going to rob someone, it's beyond ludicrous to suggest he be punished for not being a mind-reader. You can talk all you want about hanging out with the wrong crowd - they were his freaking teammates, for Pete's sake. Who do you expect him to hang out with, the architecture majors? The science club? He's a freshman in college.