All the ARRL announcement really does is reference the FCC statement of Feb. 23.
That statement said the FCC was not going to say if it considered ROS to be spread spectrum. Individual operators were the ones responsible for making a decision. The FCC has never said ROS is "illegal" nor have the ARRL. I've had a trawl through the FCC site but couldn't find a definition there of what they mean by the words "Spread Spectrum" and it's their definition that matters not other peoples. If the FCC were concerned about the use of ROS on HF you would have thought they would have written to at least one of the US stations that they had observed using it and informed them of a breach of regulations. I am not aware that they have done so. 73 Trevor M5AKA