Complete bullcrap.

Please explain how the company snooping around in a pilot's medial records "insure[s] [sic] fitness of [the] pilot group"? That makes absolutely no sense at all.

By definition, if a pilot has called in sick, he has self-grounded himself because of a known medical deficiency as he/she is required to do under FAR 61.53.

What purported "legal obligation" does the company have, as you "suspect," to protect its customers from a pilot who is NOT AT WORK BECAUSE HE HAS CALLED IN SICK??? What liability does the company have, as the result of a pilot who has self-grounded himself and is NOT FLYING AN AIRPLANE? Hmmmmmm?????

Maybe there is an argument for providing additional medical information to prove you are fit enough to operate a/c, but that's not what the issue is here. There have been cases of this in the past, but these instances are very rare.

The concern of the pilot group is having to "prove" that they were sick. The mechanisms in place currently are subtle, sometimes outright overt, harassment to make pilots think twice about calling in sick---so as to avoid the hassle.

Perhaps some of that is going on right now, despite your protestations that it's not.