He's saying he can't get citizenship in the sense that he can't risk having his foreign bank account closed--not that he is prevented from doing so by the US government.

It has nothing to do with it. But up until now the majority of accounts negatively impacted by these rules have been owned by US Citizens, US Permanent Residence have slipped under the radar so far partly because our accounts are owned by a local national (in our respective home countries) from the perspective of the bank and partly because they just haven't done it yet.

If you change status from a permanent resident to a citizen it won't magically cause your bank account to close, but you might now be on their "list" and the US government can move easily bully a bank into closing the account of one of "their" nationals. It has nothing to do with the USCIS, and everything to do with the IRS.