Here's the "politics free" analysis of the Chinese Balloon:
First acquisition of the balloon most probably over Alaska (look up the "Track"). At which point I'm certain that both high resolution imaging and certain antenna systems (ground based and satellite) had "eyes" on it.
The Canadians (and their "Agencies") would have tracked it over Canada and when it crossed over our northern border more and more "Eyes" were on it. Could we have "shot it down" as soon as it crossed into Montana...Yes, but here's why we didn't, and NO it was not because of a hazard to anything on the ground, particularly in that area in Montana.
That sort of Surveillance "payload" very probably is not relying on storing data onboard, but was transmitting as it went. Allowing it to reach the Coast gave us time to collect the data it was transmitting (what better way to see what it was seeing...). "Splashing it" just off the coast would keep more of the payload hardware at least semi-intact, which I would venture is now on its way to Langley or perhaps the NRO...