The Navy's TPS is at Pax River. I don't have any info; haven't been in that neck of the wood in ages, but I would guess that it is simply getting put through its paces by the student pilots. They frequently use odd or rare types. Not to strictly to gather data on the aircraft (which is already collected), but to let the pilots do demo fights, fly strict profiles for data collection, practice methodology for envelope expansion, write up their reports, document characteristics, etc. So aircraft with unique characteristics are often considered a plus. Sometimes it is older types, including various MiGs. Sometimes something new.
Obviously other things go on at Pax, so testing different systems and sensors or threat simulation isn't something I would rule out. But were I to guess, I'd say it is a participant in the qualitative evaluation program training.