Apparently it's a 3 of 4 setup, so yes, one more arrest and those coins are gone (not really, but you got that one)
Then they have still enough time to update their setup to a 2 of 3.
That seems to be moving in the wrong direction. Perhaps try instead expanding 3/4 to (
e.g.) 3/7, with fiduciaries distributed in different jurisdictions and geographic regions such that it is unlikely that collusion could result in theft, but also unlikely that too many keyholders could be lost at once due to government action, earthquake, war, cataclysmic asteroid strike, etc.