Can you cite a source for this regulation?
I never heard of it?
Certainly. Here's some information about it. Looks like the FCC got rid of it during the pandemic, BTW.
FCC Abolishes World War Two-Era Tower Sharing Rule For FMs.
Americans are being urged to stay at least six feet apart, but in this era of social distancing broadcast antennas will also no longer be required to cozy-up. The FCC