Though I would have to question the logic of getting better in a pool having NO CORRELATION to getting better in open water..
That wasn't what he said.
SWIMMING OPEN WATER PEOPLE SWIMMING 1.5, 1.9 OR 3.8 KM HAS NO CORRELATION TO BEING IN A POOL AND IMPROVING YOUR 25 METER TIME
Improving your 3.8km time in a pool maybe, but not your 25m time. Look at the sets he talks about. All big numbers (120 *100), steady pace. Aiming to get quicker at swimming 3.8km rather than quicker over 25/50m.
Many of us could be faster over 25/50m if we learnt to kick better/harder but how would that help in an IM when wearing a wetsuit we elect to rest our legs. Slightly different stroke mechanics and more power required to overcome lack of legs will tire arms quicker than they are used to if you have a strong pool based kick. Suddenly you are overworking the muscles, lactic build up and bam - pace drops or you burn too many matches too early to hit the target swim split.
Specivity of training.
I swim with a masters squad on a Saturday morning and breask, fly, back and free. I am sure I could be a marginally quicker triathlete if I focussed on crawl instead. However I would be a worse swimmer and I am happy to trade a minute or two in an IM against being a better swimmer.
Wetsuit
Note my wesuit has grab panels in the forearms to gain greater water purchase. If I am grabbing more water with each stroke then surely I need more power than usual. Yes I will swim quicker but where does the extra power come from? I may have a lower drag coefficient due to better position and material of suit so it may even up a bit. This could explain a lower stroke count in a wetsuit a the muscles net output may be the same.
I don't know much about swimming but there does seem to be some logic in there.
Me..face