The issue is not whether anyone would try to render aid, nor whether they would be protected by a Good Samaritan law.
The issue is the possibility of being sued for something you had nothing to do with. For example, you were on a boat, just for a fun dive, with no connection to the person sitting next to you. They are not your buddy. You are not diving with them. But, they jump in with their gas turned off and drown. Do you get sued simply because you're a Pro who showed their card to get on the boat? Some lawyer asserts that, as a pro, you should have noticed that they were doing something stupid.
Nothing to do with making a choice about rendering aid.
And that was just a made-up example to illustrate the point of being sued for nothing to do with you and nothing to do with a decision about rendering aid.
Will you be listed in the lawsuit? Probably.
Will you be dropped from the list of defendants quickly? Probably.
Is it still a huge pain in the azz? Definitely.