It wasn't a reasonable position since we've known cats and dogs (and everything else) could catch it. (Among other reasons, but this is the most obvious for anyone even slightly familiar with previous vaccination efforts.)
For a virus that supposedly just jumped from wild animals to humans, it'd be irresponsible to simultaneously think it couldn't happen again from any of the number of species potentially acting as reservoirs.
Unless there's been new information in the past few weeks I haven't seen, one of the strongest theories about Omicron is that it's a hop back from rats that had been infected with Alpha.
For a virus that supposedly just jumped from wild animals to humans, it'd be irresponsible to simultaneously think it couldn't happen again from any of the number of species potentially acting as reservoirs.