is it ok to hold a parking space for someone else by standing in it

tangentially related but two weeks ago I was unloading some stuff from my van and put my lawnmower down on the ground behind it while i was sorting things out. then I went to the side door to grab something and while i was rummaging around i heard this horrible crunch. i looked back someone was parking their BMW right on top of it. there were like three empty spaces behind me too. kinda funny in hindsight i suppose, I was stood on the pavement helplessly doing this involuntary hands-raised, mouth-agog, wild-eyed, whatthefuckareyoudoing!?! crazy-man type of gesture. and the driver was just looking at me going 'well i didn't see it!' and doing the upturned palms shruggy thing. i am not good in those stressful situations though, I started getting tearful and that made the driver get tearful too and then we hugged and chatted and made friends and then I had to go and buy a new lawnmower.

My car's alternator died in the right-turn lane during rush hour. People kept lining up behind it and honking at it when it wouldn't turn, even though no brake lights or turning indicators were on (and I was watching from a nearby store, waiting on a friend.)

So I found a sidewalk sign for an upcoming Art Walk and placed it behind my car. No more honking! People now saw the sign as the obstacle, not the car.

Which explains why while the cops never stopped (which was a relief), it was a truck with yellow lights from the city's sign department that finally showed up and helped push me into a parking lot.

Park in the middle of the street? Whatever. Mess with one of those sidewalk signs? Someone's going to get to the bottom of this!