So I registered my motorcycle in MA early this year but left the country before I could get the safety inspection, and I won't be back until next year. Does the Mass gov check automatically to see if registered vehicles are inspected? Is there any sanction for registering vehicles but not getting them inspected? (I won't be riding it before re-registering it next year, I'll get the inspection after that)
I believe the RMV can see that your motorcycle is not inspected. If you log into the web portal, you can see information about your inspection status, so they can see it too.
From what's said here
Driving any motor vehicle without a valid inspection sticker is a traffic violation.
I suppose that means if you are not planning to operate the vehicle, you won't be fined. To be sure, you might want to just contact RMV.
Registering a vehicle for ownership and registering it for driving on the road are two different things.
If by "registered my motorcycle", you mean that you registered the ownership when you bought it, then it shouldn't matter.
Safety inspections (and liability insurance) are required when you register for a license plate, which allows the vehicle to be driven on public roads.