Right before the shut down a very racist remark or two was made about middle eastern people, a person or persons got offended and made some threats, then the forum went down. I don't know if that had anything to do with the shut down, but the timing is right.
There have been reports of a bandwidth problem as well, but BT has a bandwidth problem every month's end and shuts down for 24 hours, give or take. It has never shut down due to bandwidth during the month and in the past, Matt has always posted a notice explaining the upgrade, shut down, or repair, there is no notice this time.
BT has always been profit orientated, with the auctions, ads, donation drives, an old who's who that required pay for listing, and other such ventures. Not that there is anything wrong with trying to turn a buck, but maybe it just wasn't paying off?
Could be any reason or none at all, as long as everyone is well and healthy, it will work itself out one way or another.
Will