I'm not going to say I told you so, so I'll just quote what I said in 17-1 ....

I feel like everyone is missing the most obvious thing. What if the base is trap for humans by humans?

Just because someone spray painted "rescue" on a wall doesn't mean they will be nice. Most likely they will be like the Mallers and want to dictate/rule over the survivors. I highly recommend some recon before making contact with this group.

At this point with the Zombies withering away, the survivors' biggest concern should be surviving in a post apoc world. This includes invoiding become a slave to the new King of LA.

Just my instinct
No one thought the guy was trying to WARN them not to come to the base?

"If you last a week then talk to me..." - Does this indicate that they are:
1. Experimenting on people
2. Eating people
3. Constantly in threat (probably not)

Hmmmmm ..... very troublesome indeed.