Cleaning the engine with kerosene

Couldn't see why not.

That's what I do to flush out the lower unit of outboards. So I don't see why it would cause any harm. Just a bunch of gears and bearings in the outboard, and just a bunch of bearings in the engine.

The only risk you chance, as far as I know, is if you left it in for a month or longer. Doing so is not good for the crankshaft seals. Kerosene is a petroleum product yes, yet it also has solvent characteristics. The seals are oil reststant, not necessairly solvent resistant.
FWIW, never clean something with rubber lipped seals installed in it with brake cleaner. That kind of solvent is very detrimental to seals. Carburetor cleaner however is not as harsh to them.