There is no excuse for the governor not to have known the protocol. As for regular folks, normally at a Catholic Mass when the priest knows there are many attending who are not Catholic (wedding/funeral), they will announce diplomatically that Communion is only for Catholics who are ‘in a state of grace.’ That means Catholics who’s been to confession and had their sins absolved.
The reason Communion is exclusive to Catholics and only Catholics in “a state of grace” is that Catholics believe the Communion host they are receiving has been ‘transubstantiated’ during its consecration into the actual body and blood of Jesus Christ, not a symbol of the body and blood of Jesus Christ, as non-Catholic Christians believe.
when I go to a Catholic Mass, I just sit back in the pew and let Catholics who are receiving Communion go by me. It’s not a big deal to observe that respect for their faith.
Bill Clinton took Holy Communion in Africa when he was president, and said he knew more about Catholicism than the Pope or Bishop.