The FSF decided to investigate this AR9271 part. I'm not sure why.
The AR7010+AR9280 NICs are dual-band. There's AR7010+AR9283 NICs that are 2x2 2.4ghz only. The AR7010+AR9287 NICs are also 2x2 2.4GHz only but support a few newer things (like short-GI in 20MHz mode, and generally better behaviour all around.)
Hopefully the FSF certifies the AR7010 based firmware devices too. But, they've chosen this one and I'm glad they saw it through.
I don't know if there's a hardware list that shows the dual-band ath9k_htc hardware. But it's out there, somewhere.