That is simply not true. Even without the headshotz all his abilities hit for 6k+ on a geared tank. Fresh 50 tanks get GCDed.
Flurry of bolts hit hard, yes, for up to 6K not absorbed, but all level 50 tanks spec have defensive abilities, and should have Daily mods on orange gear. It's even how Bioware describes the progression curve at level 50. First get some gear from daily, start the easier HM, and then jump to harder ones till you're ready for stuff like LI HM.
It would make no sense what so ever if you could just go and farm all hard modes in level 45 green gear, which is eventually what will happen if people continues whining because "omg that's too hard".
I've seen Ironfist being tanked by dps countless of times, and I've myself tanked him as a dps. You just need to know when the burst will happen, use your defensive CD, and hence and repeat. It's an harder fight than T5 I won't deny, but my point is that it's called hard mode for a reason, and certainly not to be farmed in green gear.