Europe and Canada Are Finally Saying No to the U.S. F-35 Stealth Fighter, Motivated By a Desire For “Strategic Autonomy”
(nationalsecurityjournal.org)
From your source:
DND spokesperson Kened Sadiku said no such switch existEd on the aircraft, but he did acknowledge that the U.S. was in charge of both software and hardware upgrades for the planes.
Emphasis mine. Countries can produce their own hardware replacements for the F-35; even without domestic manufacturing, we can source parts from any other country that has the F-35. The issue isn't maintenance in the sense of keeping planes flying, it's maintenance in the sense of keeping them relevant. And that's a very real issue, and very real reason to consider shutting down the deal. But to call that a "kill switch" is to stretch the English language to absurdity.