Does the fact that the meter is plastic make anyone else feel safe? I would stick a 8$ Chinese meter onto AC mains even if it couldn't handle it. Something inside the meter may pop but its little risk to me if I'm only holding plastic. I wouldn't leave it connected or use it again but still plastic is great insulator. If it was an old piece of equipment with a metal case I would never do that. In fact I'm always extra precautious with metal case anything because they used to tie AC to the chassis or connect it through a by now leaky cap.
It's all good unless the cheap plastic meter has internal issues,
perhaps a loose screw or washer,
or flaked off excess solder blob,
faulty dial or switches,
a combination of the above,
issues that may happen at an inconvenient time when you stick it in the AC mains
and the meter goes BANG! in your hand
and if you're extra lucky, the flying dial and plastic shrapnel will just miss your face,
either way it's not pretty,
and unfair on the people around you if you get badly trashed