I like mopeds - only need visible tread!
I think they should leave the minimum where it is. I’d personally change my tyres at 2mm and buy some half-decent ones, not teflon specials.
A tyre is only useful when it’s in contact with the road. Should be more of a test at MOT time to dampers on vehicles. I never seen a MOT tester bounce a corner. They just seem to visually inspect them.