Wow, were there really still 21K military votes to be counted?? Even at 55% of those votes (which is probably well on the low side) Burns could have picked up at least 2,000 or so votes there. If he's conceding with 21K uncounted military votes that is really nuts.
It is very unlikely the few remaining votes will go to him.
Therefore, it is time to concede. If for some odd reason he wins, then he can take it back. Concession is just words. If you win after you concede, you still win.
Maybe that's the total for the entire nation. It's obviously not the total for Montana -- the entire state population is less than a million; obviously, the number of people in the military, and serving overseas, and who voted, and whose votes haven't come in and been counted yet is not over two percent of the entire number of warm bodies.
Anybody who actually thinks for a moment instead of parroting something they (mis)heard knows that this figure is ridiculous.