Ok, think of all the possibilities.
As you pointed out the holders don't work very well so is the likely hood higher of you you transmitting a disease, which if you had you likely wouldn't be diving anyway or or handing someone a non working reg because it's full of crap from dragging.
What is the likelihood of a OOA diver panicking and taking the reg with bubbles coming out any wise (never experienced this myself but know of it happening)
Think of all possibilities and when it comes down to it dive the way YOU are most comfortable.
As you pointed out the holders don't work very well so is the likely hood higher of you you transmitting a disease, which if you had you likely wouldn't be diving anyway or or handing someone a non working reg because it's full of crap from dragging.
What is the likelihood of a OOA diver panicking and taking the reg with bubbles coming out any wise (never experienced this myself but know of it happening)
Think of all possibilities and when it comes down to it dive the way YOU are most comfortable.