If you dismiss 1.35 billion Chinese from the equation, then you have a point. Which would make your example analogous to the Norwegians not being worried about the NAZIs in 1938, because Hitler would first have to fight his way through the more populace and more powerful (on paper) French, British, and Poles. That worked out pretty well for the Norwegians as I recall.
Except that to get to Norway Hitler only had to make his way across essentially unarmed Denmark.
As you hopefully know, the Germans did not defeat the Brits and French in order to get at the Norwegians. They attacked Norway while the Sitzkrieg was still in effect on the Western Front.
My point is that it is pretty darn ludicrous to think that Pakistan poses a realistic conventional military threat to Bangladesh.
Now if they could get one over there, I suppose they could nuke Dacca. But I’m unclear why they would want to.