To be entirely fair, there is missing money in at least one escrow transaction in which minerjones was a part of.
I don't think it would make much sense to start out with one of the keyholders who has a history I describe.
Considering that minerjones is statistically the most trusted member of the forum, who has escrowed large amounts of BTC for the forum, I'd say that he is a pretty good pick. Regardless of that though, anyone could have been picked in minerjones' place and it wouldn't have made a difference provided that the other keyholders are trusted enough to not conspire with them to steal the coins.
I'm absolutely sure that theymos did his due diligence before picking the keyholders considering the massive amount of money at stake.
The trust ratings/lists are manipulated through coercion. If the
other keyholders are trustworthy enough to not collude with MJ, then theymos might as well allow there to be only 4 keyholders.
There are unfortunately very few people who even come close to being trustworthy enough to be a keyholder. I presume it was not desired for theymos to be one of the keyholders, and he was one probably because of a lack of trustworthy candidates.
Potential replacements for MJ would include, in no particular order:
Dabs
philipma1957
DannyHamilton
TwinWinNerD
qwk (I am not sure if he has held large amounts of others' money)
smoothie
RHavar
There are drawbacks to a number of the above people, inactivity being one of them.