This can't be true, right? People quit without two weeks notice all the time (just as people get fired or are 'let go' without notice all the time). If you want to leave on good terms, sure, give some notice, but there's no obligation.
It's difficult to compare professional wrestling to a real world job. In the abstract, someone like Punk walking out to never return is odd (though, as many have conceded, we still know very little about all this), but (i) this is still a business full of carnies, why do I care that they may have been burned by one cog in their wheel doing what he thinks is best for himself?; and (ii) in a conflict between HHH and pretty much anyone, most are going to side with the latter, especially when the feeling is that Punk left because he didn't want to be in a program with the man (which seems...understandable). If he's unhappy, on autopilot, etc., what other leverage does he have?