I think he is referring to the axis tank advantage caused by fuel caches.
Topic about abundant resources arises each time 3v3/4v4 discussed, and each time people rising it fatally wrong.
Fuel caches benefit allies more than axis for simple reason if allies manage to pressure and bleed their enemy caches is overall best thing to invest their mp lead into. And if caches will be nerfed, or income nerfed, it would cause exactly opposite effect those people expect it should do.
I think everybody knows that axis, notably OKW can use mp much more efficiently than any other faction, and whole "reduce income" proposal is basically "increase mp income in exchange for delaying tanks". So they want to give axis more mp, and at the same time delay allied tanks which can bleed/push axis from the map, on top of that believing those changes would somehow help allies.
Only resource income which could be reduced in 3v3/4v4 is mp income, but then it very tricky thing to do without hurting USF/UKF progression too much.