I'd suspect that anyone expected to have an audience with the pope would be questioned and/or briefed ahead of time on protocol, pretty much like visits with the QoE, if one were to be knighted, or something. Just what the "relevant" world needs, is for the QoE to order someone to kneel (like Ronald Reagan), and have them not do it. I'll never be asked, so it's a moot point, either way. Tim Minchin said it best- "Fuck the Pope, fuck the motherfucking motherfucker".
If you get to thinking you’re a person of some influence, try ordering somebody else’s dog around.