So tonight I queued for SM KP, after a few hours of people declining (pretty sure someone was griefing the queue for a while there), we finally got a full group. Immediately upon entering the instance, someone disconnected immediately and did not return, leaving us with 3 DPS. We queued for a replacement and proceeded to clear trash. After waiting in Bonethrasher's room for 5-10 minutes, another person, a tank, left without warning, leaving me as the only tank.
We waited around a little while longer, and eventually my friend, who is a Commando healer, unequipped his weapon and began attacking Bonethrasher with the Legacy melee attack emotes. Having nothing better to do, I decided to actually try, and I was quite surprised that we were able to hold out. Without his assault cannon, my friend could only use one weak heal, though we had a sage healer who was healing. Almost immediately, one guy died, another DPS, a sentinel, I think, leaving us with only 5 group members, despite this, we carried on! The Gamorrean guy was eaten by Bonethrasher a few times, but still, we survived! It looked bleak when the cat adds showed up, but still, we survived! Someone had the presence of mind to combat revive our fallen dps, but he died again shortly thereafter.
Finally after what had to be well over 10 minutes, Bonethrasher fell to the ground, dead. He did NOT enrage, leading me to suspect that he does not have an enrage timer at all, or if he does, he might as well not. One group member was disappointed as he thought that Bonethrasher dropped Rakata headgear, which my friend told him only happened in Hardmode, so at least some of us weren't outrageously overgeared. I was in mostly black hole with a bit of Rakata and a Columi main hand, my friend healing was largely the same, though he did not actually have the weapon equipped during the fight. I cannot speak to the gear level of the rest of the group, though. Just thought I'd share this as I thought it was funny that we were able to clear this with 6 people, one of whom was dead for 80% of the fight, and with a healer who couldn't really heal.
TL-DR; I cleared SM Bonethrasher in a LFG group, which during the fight had only 6 members, one of whom was dead for the vast majority of the fight, and another of which was a healer who did not have a weapon equipped and therefore could not even use most of his heals.