Okay. What threw me off was the Trig website where it says:

"The TN72 GPS receiver is a fully certified product (FAA TSO-C199) designed for voluntary equipage and use in areas OUTSIDE of designated or mandated ADS-B airspace."

I took that to mean that TABS could NOT be used INSIDE 'designated or mandated ADS-B airspace' and took the marketing statement as a distillation of applicable FAR. Class E airspace above 10,000 is INSIDE ADS-B airspace. (It is perfectly clear that TABS does not satisfy the ADS-B 2020 mandate.)