strawberry78's answer is excellent. What she said.

I would just add that I have a lot of friends who are cops, and ex-cops and they joke ALL THE TIME about how stupid it is for people to put their hazards on. Putting your hazards on does NOTHING to shield you from the wrath of the law. On the contrary, it DRAWS ATTENTION. Nothing says "Hey, come look at this and write me a ticket" louder than big flashing amber lights on all four corners of your vehicle.

You should just find a regular spot, but if you're going to be a dick about it and take up half of the wheelchair space for a minute, you're better off just leaving the hazards off. Why advertise your illegal behavior?

Hazard lights or or no, if you've left your car there, it's parked and that's an infraction.

It's just one you're likely to get away with.

I wondered what you would have done or said if, when getting out of your car, a person who really NEEDED to use that disabled person parking spot to have access to the library was waiting right behind your vehicle?

What would you have done if you saw them just driving in the parking lot at that point, but they hadn't seen you yet?

If those actions are different then what you did, when no obvious person was immediately waiting for the spot, why?

I have known quite a few persons with significant disabilities that would have jammed their vehicle next to yours and dropped their wheelchair lift down so that it blocked you in as they left their vehicle. Just as an object lesson. But you wouldn't necessarily have to worry, they might be going in for just a minute or two. But then you never can tell how long things may take.

I don't mean to be too abusive. It's just you only had to deal with a "catty old woman". It would be decidedly much less comfortable if you were dealing with a person that might dress you down from a much more significantly superior viewpoint. Not having that spot available could be as effective as if someone had locked the door would be to you in being able to utilize the library.