Opinion stated as fact.
After some 33 years and 12,000+ hours on bass, I keep myself limber by playing in front of the TV. Sure, I'm not learning 1973 Zappa parts, but how is keeping your fingers moving on your bass ever a bad thing? I play primarily fretless and my intonation is not suffering, and when a commercial comes on, I immediately shift to trying to cop the bass part (you'd be surprised at how many commercials have interesting bass parts).
Now, I wouldn't recommend learning to play bass in this fashion, but you stated unequivocally that it is a waste of time unless being used for ear training. Interestingly, I would find playing in front of the TV completely useless for ear training, and I play fretless. But I'm living proof that this is not a complete waste of time. I believe my playing has improved over the past 4-5 years as much as it has over any period of my development.
In many cases, this is the only private practice time I can manufacture during the week, and I still rip it in rehearsal or in a gig. My wife grew up in a musical home and she actually likes to hear me noodling around on what-not. So, I can hang with her, get some finger work in and watch the Broons.
Believe it or not, this approach actually helps me foster my #1 goal in my approach to playing music: don't think; react. By concentrating on something other than my bass, I can develop this sense of "detached connectedness" with my bass when I do not have this other distraction at a rehearsal or a gig. The net result is that the music just comes out. Ain't always good, I'll grant you that, but this is a work in progress. It's working quite well for me so far. Again, I would not recommend this for learning the instrument, but for maintaining chops, it should not necessarily be discounted in one broad swipe.