Jenner didn't tell them anything Eugene wouldn't already know. The one plot hole I see is that Glenn was at the bar with Rick and Hershell when those two guys told them DC was completely overrun.
Also, maybe Glenn didn't want to dash their hopes and dreams so he could start looking for Maggie quicker.
There is no flippin' way Eugene knows what Jenner whispered to Rick. They are both scientists but, no, I don't buy that Mullet Man knows more than someone "in the know" at CDC...
Unless they clear this up when Abe's crew meets more of Rick's crew, I will just write off to a plot hole missed.
I've always had a problem with the CDC sequence anyway since Kirkman has said numerously and consistently that we are not meant to ever know what caused the zombie outbreak. What Jenner whispered isn't the cause but is close enough.
Btw, loved how Abe referred to them as corpses.
We now have
Walkers
Biters
Corpses
but no reference to "zombies" that I can recall by characters in the show. I think that I may have heard "monsters" or "things" but not zombies.
Glenn doesn't know these people. Glenn's also not stupid. He's not going to stand there and debate who's information is more valid. If the guy doesn't want to volunteer the information that he's using to drive his group northeast, then Glenn's more than happy to find his wife and leave them to their quest.
Eugene was far to quick too say "Let's follow Glenn" and had a little smirk on his face as they left the truck because he was given some time off from his ruse of being a "government scientist". Achy-Breaky looked downright pleased that something derailed his group's trek to Washington.
Oh now you had to go and make sense and point things out that I missed. Dammit Jim I'm a comic book fan not a doctor. oh wait, you're Chris.