Dear Hakatan,
If it comes down to mesorah than I probably outdo you a thousand to one. But it comes down to shimush. You have to know how your own leaders apply their standards to themselves, their peers, other leaders, the laity, the unobservant, etc.
1) His position is stuck in a lot of tough public conundrums. This is nowhere near the toughest call he had to make. If it is so obvious to you that it is forbidden regardless of context, wouldn’t we be obligated to be convinced of some outrageous explanation to avoid lashon hora?
2) I never meant to insinuate that it is permitted. Just that it is unclear the reason of the issur. Can you provide the reason from today going all the way back?
PS What if R’ Murvis went into a church to meet with a priest on a matter of religious freedom?