Respectfully, you are incorrect or misinformed on many points.
- coinbase is and has been a licensed MSB for several years, this means that it has already had to comply with all of the same BSA rules as every other bank. [1]
- Banks don't have to report ANY transaction over $10,000. They have to report every CASH transaction (or aggregate of transactions) over $10,000 and any Suspicious transaction (or aggregate of transactions) over $2,000 [2]
- coinbase is rightfully concerned about the breadth of the subpoena because it's a giant fishing expedition. In order to request records, the federal government SHOULD have to provide reasonable proof of suspected criminal activity. [3]
- finally, this has absolutely nothing to do with anonymity. This has everything to do with another drastically over-reaching request by the federal government for personal information even when there is no evidence of any specific crime.
[1] https://www.coinbase.com/legal/licenses?locale=en
[2] https://www.ffiec.gov/bsa_aml_infobase/pages_manual/OLM_015....
[3] See the Constitution.