The US Senate banking committee wrote a letter to facebook questioning about the nature and legality of it's cryptocurrency project code named Libra.
https://www.banking.senate.gov/imo/media/doc/5.9.19%20Facebook%20Letter.pdfThey essentially asked whether it would enable users to have privacy and would make it harder for the government to monitor every personal and financial moves of people in the US and around the world.
Though the PDF contains a bit of different set of questions, your deduction are easier to understand. I'm a crypto enthusiastic but also believes that it should have full support from the authorities. The nature of crypto that troubles our establishment should be modified for the greater good.
That is the trendiest question in almost everyones mind whos in the politics or deals with the monetary policy or is in the Federal Reserve. But an entrepreneur would not do anything but for money and maybe Mark wants to be part of the growing trillion dollar business which might be the reason behind the idea of FBCoin. I think he should do it.