NORAD isn't a first strike command however, it's something to realize that Russian bombers incursions into our airspace are typically escorted by their own fighters. Currently those are last generation SU-35's typically however, Russia is actively producing its own 5th generation SU-57 fighter that while likely stacking up poorly against the F-22/F-35, is an exceptionally dangerous adversary for 4th generation fighters like the F-16, F-15 and Gripen. 5th generation platforms are being developed and sold abroad by/to adversary nations, the future is already here and it makes little sense to address that by.......buying an aircraft already behind the times? Sitting back and expecting the status quo to remain such for the next four decades or more does not seem responsible.
It's also something to put out there that the RCAF has a history of expeditionary operations with the CF-18 which has the potential to put us up against increasingly advanced hostile SAM, drone and fighter threats abroad. A 5th generation stealth aircraft is leagues more survivable against threats at home and abroad. The RCAF deployed in the Gulf War, Yugoslavia, Libya, fighting against ISIL, etc. With tensions flaring abroad and our Govt in trade/relation building talks with countless nations, I wouldn't expect the RCAF to be sitting on its hands in the coming decades. You could do this work with an aircraft like the Gripen however, you are fundamentally bringing a much less interoperable, safe and capable platform to the table to do so. Given the breadth of allied F-35 operators (Australia, Belgium, Denmark, Italy, Japan, Netherlands, Norway, Poland, South Korea, UK, US currently with Czech Republic, Finland, Germany, Greece, Romania planned for the future), arriving in Europe or elsewhere with a fundamentally interoperable aircraft is an advantage hard to put into words.
F-35 isn't some crazy new capability for many nations, it's simply the new norm and has been for quite sometime.