Not sure if it's already been answered, as I haven't made it to the most recent page.
Sounds like you've already considered the options but why can't you just transfer to the intended airline? Unless you are worried about the expiration of the points? Pretty sure I will flick mine into Krisflyer once my MR program card ends - but then I have a small balance.
In terms of BMW Gold - anecdotally it doesn't sound like he would receive it. However, it might be worth confirming whether it was linked to Gateway, e.g. I had CA Gold (which could have been linked to Gateway) but it was directly linked to QF instead and I was fine.
I'm glad at least one other person seems to understand where I was coming from
As for updating the wiki, seems like a regular who doesn't want repeated questions will need to update it - given the 90 day, 100 post count requirement.