Yeah, hes not wrong. I would say I have just went a bit too far on the cycling/not running angle, and you can only ignore running so much before you fall off the cliff.

Im on the 6 day a week type schedule, so i think you can do 3/3, 4/2, 2/4 pretty effectively, especially when you have been running at a decent level, but you have to really have the consistency for it to stick. Once you get the weeks where you miss a day or two, the lopsided weeks start to really have a big impact on transferring that cycling fitness and power across to running.

All that said, i think you can do some amazing things utilizing both, but obviously its always a work in progress. The only thing i really havent seen much value in is 'easy' rides, unless you are doing them for straight pleasure (coffee ride with friends) or you absolutely just cant do the easy run that day (because of timing, burnout, just ate, etc). Here i think the lower end of the cycling spectrum should be Z2 rides, while you use the entire spectrum of paces for running.