[16:54:29] Fo would not approve of that.
Fo priests are unable to reinforce cave walls and floors due to restriction, even though they have no restrictions on mining. I thought this might've been a paving restriction but I tested with a Libila and Magranon priest, and they were able to reinforce the wall with no restrictions.
I suspect this is a leftover from when Fo priests were unable to do mining before the priest rework.
This also applies to cladding cave walls.