[dpifke]

Interestingly, TreasuryDirect's terms of service are codified in the Code of Federal Regulations:

https://www.law.cornell.edu/cfr/text/31/part-363/subpart-B

From a brief reading, having a third party access your TreasuryDirect account does seem problematic:

https://www.law.cornell.edu/cfr/text/31/363.22

https://www.law.cornell.edu/cfr/text/31/363.17