I think you're oversimplifying things. PI was right there in the pack until early YR3. They were within a few k acres of Emeriti when their cf was nearing notice time and they warred Gods in the war that CR hit Gods into. After PI won that war, Emerit's cf with PI up. Emeriti asked BB for a cf extension so they could afford to give PI an extension to give them more time to prepare for war. BB refused.
Emeriti then considered extending PI to fight BB first, but CR's cf with PI would be expired by then and so Emeriti worried about CR farming them. Emeriti told PI if they could get a CR extension, Emeriti could extend them. CR wouldn't extend PI so Emeriti felt they couldn't afford to either.
BB and PI then made a deal to war, despite their in place cf deal, to dodge Emeriti. Emeriti stayed out despite no cf/notice in place with PI and let the war take place while sitting and waiting for the winner. After the war, BB was on #1 land and left post war early to surprise attack emeriti before they were ready, but it wasn't enough.
I don't think you can really fault Emeriti for who they fought when you consider all the details.
Edit: Also, in defense of PI, they had already won 2 top wars this age by that time including one vs Sparta. They were in a bad position, but it's not fair to imply they couldn't compete in the top.
(fixed locs)