Qualified Mechanic???

If he’s never worked or been to a Rotax school on a Rotax 912iS then he isn’t qualified. He will not know what or how to do things and I doubt he has a dongle and laptop computer to download fault logs and do an diagnostics. Even on the 912ULS and UL many untrained and I know everything mechanic’s make bad decisions. I would also bet he doesn’t know where to find SB’s and won’t use a Rotax engine checklist. 
You can quietly test him. Educate yourself on a few procedures and then ask him some questions.

Think of it this way. An auto mechanic that has worked on nothing, but old VW car engine’s was just given a brand new Cadillac car to work on. They both have four wheels and get you to where you want to go, but are two different animals. 

I have tested him.  He states the Rotax is simple and he does not need the training.  That is a hazardous attitude. 

Even after training there is a learning curve.

Here is a for instance. Simple oil change. If he treats the Rotax like another engine he will do it wrong. If he heard he should rotate the prop to return oil to the tank he may do this when he has already drained oil out of the tank or when the oil filter is off.

Ask him to detail an oil change.

Ask him something simple about which spark plugs to use and or depending on which he uses the electrode gap and what will he use on the threads. What manual will he use to answer and perform an inspection and where to find it.

These are all very basic questions.

Is this the same person who told you that an illuminated Lane B is no big deal?

Yes