To “crash” a meeting or a party it is assumed you are not invited. This is a PUBLIC meeting, therefore the entire public is invited. If it was held on public property and no fee was paid for the property usage then all are able to attend. Perhaps if it was advertised as a “Democrats Only” or private invitations were issued it would be considered crashing but still, if held on public property and without charge then it seems all are legally able to attend.
If Dems want to hold their Town hall meetings on private property then it would indeed be crashing on the part of the Conservatives. But if they were held on private property they wouldn’t really be “Town hall” meetings would they?