It may depend on how the offloading is implemented, but we do have a mechanism to force the audio stream off from the qc_usb_audio_offload. Regardless of if the UDEV is suspended first, or the USB backend, as long as we ensure that the offloading is disabled before entering suspend, I think that should be sufficient.
The reset_resume() path is fine. Bus reset is going to cause a disconnect() callback in the offload driver, in which we already have the proper handling for ensuring the offload path is halted, and we reject any incoming stream start requests.