I think he mentioned something like that on his blog, it makes for very good reading, I'm not sure if he's still writing his book but if anything like that would come out, it'd be in there or his blog.
If all else fails comment his blog and ask, he usually responds. I can see TG doing that. But Bob Jenkins also commentated CART as well however and he went on to do IRL with no (visible or documented) friction with TG.
TG absolutely hated the CART medical crew who were under contract to the Speedway during the split, never mind they were there pre CART/IRL split and had been there since the USAC/CART split (Steve Olvey and his staff) and treated them like dirt whenever Indy/NASCAR/F1 rolled around. For instance he tried to do that to them at the USGP by not letting them have anything to do with the race at all, so they were in the hospital but the FIA medics took over, this was 2001. Bernie had the last laugh however and flew them all to Brazil pretty much as VIPs, So yes, TG is enough of a control freak to do that.
From watching the broadcasts Paul was nothing but professional covering both, if ESPN had contracts for both CART and IRL he couldn't really say no could he, as he'd get told what he was covering.