Doc -- I know a lot of time and money may be expended in breaking the chain, which is why we all have liability insurance that covers legal costs. BUT, even though the docs don't necessarily believe it (as you know I'm married to one), plaintiff's attorneys also go through a significant screening process to determine whether to take a case -- in no small part because THEY have significant costs too.
It is my belief (based on nothing whatsoever except logic and faith in the system (misplaced though it may be)) that it is the very rare plaintiff's attorney who would attempt to sue a doc for "advice" they gave online in a Scuba forum. Why? Because the chain should be broken so easily and if broken so easily, it would not be worth the time and effort (remember also most people would NOT be in the same jurisdiction so there could be significant cost just from that).
Thus, unless your personal risk avoidance is really high, advise away.