Yeah, I think we're in agreement on that! As I posted on t'other thread, my HR on a flatout 5km is waaaay below what I can do on the bike for a longer TT, yet my legs are fecked afterwards. (Hopefully the gap will narrow as I get more 'run fit' - but it won't close until I do as many foot hours as bike hours.)
It's even worse for us forefoot strikers, I suspect, what with the calves doing even more work.
(I can ride pretty well after a hard run, but I probably lose a little top-end. Compare with when I ran the day after a steady 200k recently; my calves were complaining throughout, even plodding.)
I really don't think running is 'good' for your cycling - or Sir Brad would be doing it! It's really a mental thing - you might run when you can't be arsed* to ride, it will help keep weight off and give some CV benefit (compare to sitting on the couch).
*or conditions are just too dangerous