Actually I've seen this a couple times now, abet on a much smaller scale. I have coaxed octopus' out of their holes and let them climb up my arm. Where upon I get some nice shots. On a several occasions I've had people (usually divemasters leading a group) come and rip the octopus off my arm. A couple times the now very aggitated animal has gone to the offenders head, pulled their mask off and then pulled on the regulator. On one occasion a particular DM has his ears drums punctured for his trouble. These were small animals maybe 12 - 18" in length.
As far as pulling a regulator out, they seem to only grab the hose, as they really do not like anything metal. those of you with plastic regs, well, be nice. Smart animals.