Again, there must be value to China with regard to GPS data if they have spent so much effort in obscuring it for so long. Therefore it would make sense that there is an interest in harvesting it.
It shouldn’t be required of me to dream up scenarios that you may or may not agree with. You have no view into their government or our government either.
But to play the game, as you’ve already pointed out: anyone can determine military base locations without the thousands of social media accounts in TikTok that would dot those bases. So what could that give them? Correlation. I’m sure that there are plenty of different avenues they have to get intel on who works where, and as a government contractor we received plenty of training to avoid publishing it anywhere (e.g on LinkedIn or Facebook). Would a government, that harvests data for future use, limit itself to a few chosen avenues?