I'd just go and see how they are getting on before deciding what to do. You need to be pragmatic. You can threaten the law, the police, costs etc, but if their stuff is in the house, the quickest way to get it out is to let them get on with moving it.
If they're working at full pace and there is too much left to do for them to be out tonight, yes, one of you should take possession (with a mattress on the floor if need be) while they carry on, and let them back in to finish off at a reasonable time tomorrow. The rest to a hotel and invoice their solicitor, but just as a practically - don't turn it into a threat.
If it's possible for them to finish tonight, I'd either help them do so or move some things in around them if that won't be too chaotic
They still own their stuff and your recourse is to give them reasonable opportunity to remove it. You don't have the right to keep it, smash it, hurl it onto the lawns or chuck it into vans.
See if they are faffing trying to clean too late in the day and tell them not to bother. Tell them what fittings you don't mind them leaving. I got all my curtains, blinds, lightshades, mirrors and a dishwasher and chest freezer thrown in at the last minute in a similar situation.
Aggression and rudeness may seem justified, but they're not going to get you anywhere. You can be assertive without being hostile. Split up if it's not going to be solved in a couple of hours, remind yourself it's just one more day in the long house-moving marathon, and go for vigorous cooperation and encouragement over drama.