The police have zero authority to weigh my drone, if they asked I would laugh at them and tell them to move along!The police are going to weigh it if they ever ask you to hand it over to them as part of an investigation into a drone complaint. Should the complaint be just some frivolous Karen whinging about nothing you'd probably be fine but if something more serious happens they'll have that drone off you for analysis before you can say 'but he walked into it !'.
And that's (partly) how they catch people with illegal FCC modes in CE countries as well.