I didn't want to reuse the word 'rule.' The obvious rule here being the expectation of attributing who you're quoting.
The Rapist Trump campaign also used Queen's "We are the Champions" yesterday even though the surviving members have told them to stop and may even have asked for a cease and desist order.
Clearly these speakers are lying when they say that Rapist Trump 'plays by the rules.'
The RNC legally licensed use of "We Are the Champions" at the convention. Queen has no legal right to object.
They can object if they want to. Happens all the time.
Queen can yell to the rooftops that they object to Trump or the RNC using the song, but there is no way that they can receive a cease or desist order or legally sue for the RNC playing it. The RNC has legally paid them to use it in the arena.
According to the comments section it's disputed exactly what the Rapist Trump campaign paid for. Did they also pay for the song to be used at his rallies?
1) It's the RNC that paid for the use at the RNC. I have no idea whether the Trump campaign separately licensed the songs' use at his rallies.
2) The RNC isn't broadcasting the convention, at least on TV. It is up to the networks to decide what to broadcast on their channels. They can bleep out all music if they wish. But the networks would likely argue fair use because it is a newsworthy event.