FC's don't just get dissolved, they decay over time.
If the FC leader doesn't login after a certain period, the next person who logs inherits the master leadership.
The same goes for the house, the house gets inherited by the new master.
Even if that FC had 512 members, but none are active to inherit it, it's going to get removed.
I've seen FCs with hundreds and hundreds of members with like under 20 active members. I'm not saying yours was but they exist, those ones that spam invites and attract people who did not stay in the game.
So yea, it's not Square dissolving the FC, it's its inactivity.