https://www.reuters.com/article/factcheck-coronavirus-pilots...
If you have another source, feel free to provide it, but I've found no other source for this claim aside from Facebook memes.
Maybe it's because you're casting doubt without actually considering the evidence in front of you.
> more than 97% of its staff received at least one shot after the deadline this week.
If pilots and copilots are massively, massively over-represented in the remaining 3%, you might have a point, but that is a huge and unsupported assumption.
"airline industry" being the differentiator between what you listed and the original article's claim.
Also, the number you're referencing is United Airline's, so not even Alaskan.
> United Airlines mandated vaccines for staff in August and said more than 97% of its staff received at least one shot after the deadline this week.
All those discrepancies aside, you probably have a point. I don't personally believe it's _this_ reason alone, but I think it's at least a part of the issue.