Even with the updated info, I would not worry about under two hour connection. Unlike DFW where connecting outside of security is a real PAIN, Subway in the basement is kind of fun (though you have to look pretty hard for it because last time I was there I had to look hard even though I know it's there).

DL is in Terminal A where UA has very limited presence, though Corpus will almost certainly get a regional jet, so it's possible they would not have to switch terminals, but most likely it would be Terminal B departure.

So no worries, they should be able to make the connection even if incoming DL flight is a little delayed

Oh, and if worst comes to worst, UA has an unpublished "flat tire" rule.