As a property manager myself I have to say, we do not allow parking on our sidewalks. We pay huge amounts of money for special paving stones and to keep our centers clean. To have motorcycles parked on our sidewalks, blocking traffic and dripping fluids is a BIG no no.
That said, we do provide areas for motorcycles to park, and have signs posting where you can and cant park, as well as security that will politely let you know you need to move.
However, if we have someone feels the need to flaunt our rules or be belligerent, I have no problem calling someone in to remove the bike from the premises since it is private property as well as issue a no trespassing warrant against said offender which my security officers have the authority to issue, I dont have to call the police and in any case, being private property they cant do anything other than issue a no trespass.
Being a biker myself, I try and be as lenient as possible, but we all have to remember to respect the property of others, and there are rules for a reason.