Easier to replace because 5G is being fresh installed, imagine replacing all that fibre. It's also easier to hide possibly nefarious equipment in 5G and proxy to somewhere else, whereas the usual fibre splitters and taps nation states use are high traffic, bulky and basically impossible to exfil back to China. Fibre is "dumb" equipment whereas much of the 5G stack includes vendor software, virtualization etc which increases risks enormously.

You're not wrong.