That seems to be a popular theory making its way around the fandom, but I think this is one of the worst, most implausible theories in the history of ever. Or at least the history of The Walking Dead. Last night's ep, JSS, showed us poor Enid's backstory: The loss of her parents, her love of turtles (RIP Daryl's little shelled buddy, Anthony!) and, in the eventual reveal of what JSS means, her will to just survive... somehow. Within a week or two of her parents dying (according to the actress, as revealed on Talking Dead) she arrived on her own, alone, at the ASZ, bloody, with a belly full of raw turtle. When exactly would she have met the Wolves and hatched a plan to infiltrate the ASZ with them? That's a rhetorical question, of course, as I have the answer!
Let's go back to to season 5 when we first encountered the Wolves' handy work in Noah's neighborhood. We know they had been there recently. I know (because I live in the DC/MD/VA area) Richmond is just under two hours away from Alexandria by car. We also know, timeline wise, Enid was already at the ASZ by the time Team Rick arrived in Richmond. It's just not plausible, even if the Wolves had a car and drove straight to one of the vehicles Enid had camped out in, that they had the opportunity to meet when they were not in the same vicinity at the same time.
Not enough to convince you? That's okay.... I have more. Again, going back to season 5, we know Aaron and Daryl's adventure tracking Red Poncho Guy put them about 60 miles away from the ASZ (as indicated by Aaron). The Wolves had obviously set up shop in that area: They had an awesome sound system installed for the entertainment of the trapped walkers/hanging disco ball walker torsos; they rigged the trucks so that anyone (Aaron and Daryl) opening the trucks would likely be devoured by their walker army. All that work took some time, so the reasonable assumption is they had temporarily settled near there. This Walker Disco Trap had to be in pretty close proximity to where Morgan first encountered the Wolf that wanted his oatmeal and where he deposited the two Wolves he should have killed (hindsight is 20/20) in an abandoned car, since he's the one who showed up to save Aaron and Daryl. But.... here's the biggie* - Aaron dropped his bag near the traps. We saw one of the Wolves pick it up in the S5 finale and look at the pics of the ASZ. In last night's ep we saw Aaron discover his lost bag in the possession of a dead Wolf and realize they saw the pics, which led the Wolves straight to the ASZ. That was made crystal clear by Aaron's sad little guilty face. It was not a plot they hatched with Enid. It was a mistake made by a too Zen Morgan and frightened amateur photographer Aaron. *Bonus biggie.... the Wolf Morgan talked to said Morgan was the first person he had seen in weeks. Had he met Enid, thinking he was going to "take" Morgan and add him to the walker army, he would have no reason to lie.
Even if we threw all logic out the window (which in a show about dead people reanimating, sometimes we have to) it still would not make sense on the most basic level that Enid is a Wolf in Aeropostale clothing. The idea that she came into the ASZ to spy for the Wolves and they waited to attack until the ASZ was full of badasses is preposterous. The ASZ people without Team Rick are weak. We saw Olivia hiding in a closet, Spencer and Deanna hiding in the crashed truck (while watching/letting Maggie go off to fight the Wolves by herself), Jessie and Sam hiding in a closet... these are the people you want to attack, not Morgan and his Zen Stick Of Doom, Rambo Carol in Wolves' clothing and Gun Toting Babysitter Carl. That makes zero sense. They could have taken it any time in the three weeks Enid was there before Aaron recruited Team Rick. Easily. Without breaking a sweat.
Enid is not a Wolf. She's just a scared little girl with no family who decided running is her only way to Just Survive Somehow.