Maybe they didn't. But if their son told them ANYTHING at all about why he was home without Gabby, they should have relayed what they were told. JMO Does anyone honestly believe that they didn't ask and he didn't answer them, somehow? JMO
I talk to my brother quite often but it can sometimes take several days to get hold of him. Just because you send somebody a text, or leave a message, doesn't mean they got it.
In this situation we can add Brian into the mix. We don't know if he managed to intercept communications. Perhaps block numbers or delete messages.
We don't know that Brian's parents actually received any communications from Gabby's parents at all.