It's both:
Title 47 - Telecommunication. § 15.5 (b) [...] subject to the conditions that no harmful interference is caused and that interference must be accepted [...]
https://www.gpo.gov/fdsys/pkg/CFR-2015-title47-vol1/xml/CFR-...
Title 47 - Telecommunication. § 15.5 (b) [...] subject to the conditions that no harmful interference is caused and that interference must be accepted [...]
https://www.gpo.gov/fdsys/pkg/CFR-2015-title47-vol1/xml/CFR-...
When the FCC says you must accept interference, that means you have to live with it if the interfering device meets emissions standards. It doesn't mean the device has to be functional in the face of interference.
They must accept the interference in a philosophical manner more than a technical one.
(Of course, because I'm not a complete dick, I would assist my neighbor in properly shielding his TV or otherwise mitigating the situation, rather than tell her to pound sand.