When my starter got a bath, I had the starter removed and taken to a rebuilder for a cleaning and lube. 15 seasons later it is still cranking fine.
No water entered the Power Trim reservoir, so it wasn't messed with
The gear lube's additive package contains EP additives, these will actually aid in protecting the cam lobes of non-roller bumpsticks, since todays oils are sadly lacking these additives. So, after draining the crackcase contents and refilling with fresh oils, the trace amounts of the gearlube shouldn't matter. Of course you could put a small amount of gear oil and engine oil in a beaker, mix them and apply some heat and see if there is any chemical reaction, Of course, this wouldn't apply pressure and/or shearing to the mix