If vetoing funding for an elected official because you want them to take a specific action is criminal, then it would appear Quinn's veto of legislative pay would be illegal too...
Actually it brings up an interesting point, if you offer a financial incentive to a legislator or legislators in order to get something done, it would obviously be illegal.
For example if I said, if you pass bill XYZ each of you gets $2,000 in cash, most people and I suspect the legal system would consider that an attempt at a bribe, and if any legislator took the money, they would likely come under suspicion of being bribed.
Now lets say, I had a legislator working for me as an employee, since the legislature is a part time one hypothetically and I told them unless you voted for X you were not going to get paid would that be legal? I doubt it.
Finally, there are legislators who either work for municipalities (there used to be at least a CPD officer or two if I recall) could that municipality refuse to pay that person (or lets say withhold some sort of earned payment) unless the legislator took specific action? Unlikely.
So how are any of these really different than what Quinn did with the legislature?