This may make sense if the extended warranty is limited to defects introduced by the remote change. I.e., if they remotely break your device, they should be responsible for fixing the damage. A full warranty extension doesn't seem reasonable to me, though.

With regards to your last sentence, I think a good first step would be to require at least security and other critical updates to be provided within the full warranty period. And this would make sense even without the (limited) warranty extension, and I actually consider it more important.