Outside of your little echo chamber here which is understandably biased towards defense issues, does Canada geopolitically really give a care if the US, AUS and UK get all hot and bothered by China? China isn't actually a geopolitical threat to Canada aside from how much the US cares about them. This means the real geopolitical concern for Canada is the US (not in an enemy way, in a must always pay attention to what they do way).
And before people get bent out of shape about trade, exports to China (our 2nd largest trade partner) account for ~3.9% of all Canadian exports. UK exports are the next highest at ~3.35%. Imports from China are much higher at about ~12%. There is only one geopolitical reality for Canada that matters and that's the United States reality as focused on North America (Canada to US exports ~70% of the total, Canada imports from US ~50% of total).
I don't see UK and AUS getting all upset that they weren't invited to NORAD or any of the other bilateral deals between Canada and the US.
Finally on no! We can't be involved in secret quantum computing or AI research! So what? That's a club that would be nice to let into but not really essential. Especially considering all the big breakthroughs in that research will likely come from the normal places, a company or a university research lab.
This is basically a regional defense treaty at the end of the day.