I think they were more afraid of a repeat of the infamous Magoo incident.

If you will recall, a passenger flying out of JFK used his eyeglass screwdrivers to disassemble the spectacles of the very near-sighted pilot, a Mr. Melvin Magoo.

Tragedy was avoided by a quick-thinking FA, who gave Mr. Magoo a bottle of whiskey. After finishing it off, he found that the bottom was his exact prescription and he peered through it while bringing the Jumbo Jet to a safe landing at CDG.

Of course, this would have been even more impressive if he had not been trying to land at ORD.