Something that sounds like a production flaw to me is how the IRS gets corrupted. Sadly the article did not go too much into detail, but gyroscopes and accelerometers should not be affected by GPS data. Sure, if they do not sync up with current data, error propagation becomes a problem - especially on long flights. But i reckon gradually depreciating data is better than maliciously wrong data.

The article mentioned, that large plains have 2 GPS receivers. The spooving seems less traditional (sending wrong data with more power), but more sending a lot of incomplete data to confuse the receiver. This should introduce a desynchronization of the two receivers present, and alert the internal systems. Since it is detected, that something went wrong with the GPS, the 3 IRS can calculate the position from recorded data. This is a fallback and accuracy will depreciate. But if the pilot is aware it could still be valuable information. Additionally it is more scalable than air traffic control having to navigate affected planes.