Seatbelt laws have very limited impact outside vehicle safety. Nor does it open a slippery slope that leads to buses and trains and elevators and dining chairs and beds getting their own seatbelts.

Regulation on speech threatens the basis of democracy. The fact that the countries pushing them most successfully (UK, Australia) are also the ones with serious freedom of speech problems compared to their Western peers should also tell you that no, they will not stop at throwing you in jail for memes on twitter.