I'm sure there will be a lot of, well, let's say "visual inspection" going on to enter these town halls, if you catch my drift. It probably won't matter if you claim to be a Republican but are brown, black, female, or under the age of 50.
Party registration is public data in Arizona. They provide a ton of data, actually. A lot of states just provide name and party affiliation and maybe zip code or whatever. But you can often just buy it.
If they required people to RSVP, it’d probably be pretty easy for a political party to cross reference and check ID. (It seems Arizona sells the list to political parties and mere citizens have the right to inspect the voter rolls. Whatever that means.)
They'll just fill the place with known loyalists, party officials, and MAGA social media influencers, denying access to actual republican voters.
They'll be quiet and listen to their master like good little boys and girls, and then they'll go on social media and say "see? our town hall was full of republicans and it was peaceful! your town hall must have been infiltrated by socialists!"
The town hall outrage will just become another charade, if it hasn't already, very very soon.
I had to check in at the door at my reps town hall in nys.. There was a list of folks that rsvp. I got the invite by email, so I bet it's based on voter registration, and if you walk up at aren't registered R, no dice.