Kind of an interesting question. Unlikely the frame of your rotary cutter provides full drawbar capacity for your tractor but it is sufficient for some light pulling. Not sure it’s a “one size fits all” answer, particularly with family and someone who might use your equipment occasionally
My reaction would likely depend on the operator. If my brother did it, I wouldn’t care. I know his skill level and have great confidence if he judged the load to be light enough for that to be acceptable it was acceptable, otherwise he wouldn’t have done it. I wouldn’t even mention it to him at all.
If a less experienced operator but someone who respects the equipment and is still learning, my wife for example, I might have some questions and some discussion about the appropriate thought process and alternatives if their thought process needed adjustment or confirmation they got it right if their thought process and decision was good.
If it was someone who did it because it was convenient, they don’t respect the equipment, and they still don’t give a crap after a polite discussion, they wouldn’t be using my equipment in the future.
Only other thing is if you’re REALLY particular about your equipment; as in it doesn’t matter if it was a log or a twig, you do NOT ever want to see a chain scar on anything other than a shackle. If you’re that particular and you know it, I would suggest never letting anyone borrow your equipment.