AC43-13-1b Chapter 11 calls out terminal blocks or studs to have "adequate" clearance from structure. It does not say what "adequate" clearance is. AC43 goes on to say, if there is not "adequate" clearance, you can place an insulator between the terminal and structure.
The only risk I see to the way you have it is if the terminal loosened and rotated against the engine mount. If you place an insulator there, that risk would go away.
Sorry, but that is the best I can do. Perhaps a few stronger opinions will chime in.
Smart People do Stupid things all the time. I know, I've seen me do'em.
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