well, if somebody released you from a trap (that you may have been stuck in for days) wouldn't you react by feeling a bond of friendship? running off wouldn't be my first reaction. nor do bobcats get a prey response from humans (thankfully), unlike some of the larger cats (doing this with a tiger or a lion or a jaguar or a cougar probably would have gotten these guys eaten).

so, i think what the bobcat saw was some new friends and wasn't particularly keen about leaving them behind, before the truck scared the fuck out of it (caves aren't supposed to roar. da fuck? i'm getting out of here!). it was roaring, but that's a bobcat being a bobcat. it's a shame they didn't give it a bit more time before scaring it off...