While that’s basically true .. good manners would dictate consulting with the organizer of the rally .. to see if it would be okay if they also participated.
But, as the GOP-e always shows us .. they do not have good manners .. nor do they play fair (they learned a lot of it from the DemocRATS).
So, they can try to mess this rally up .. but they do so at their own peril.
By participate I guess you mean since 14 or 15 other candidates were
not given “prime speaking time”, you think that’s “Bad Manners”?