Possibly Shannon is now terrified of speaking to Naomi - she might be another sister he totally socially fauxpaus'd at, she could even be his MOTHER in disguise. He just doesn't know.
...none of that is true, and nor appropriately serious. Starting over, Shannon is greeted loudly and vulgarly by the younger of the boys before they're piling out of the van like puppies, and this time he just saves himself the trouble and asks: it's Kieran's little brother, now grown up too, or trying. Because that's what happens when a person doesn't come home for a decade. There's a cinematic quality to all of this, the prodigal son archetype floating just out of vision. Shannon steadfastly ignores it and lets Liam load his bag into the back of the van, hanging onto the camera equipment himself.
That accomplished he slides open the door and really absorbs Naomi's existence in a three dimensional way; practiced at noticing everything he can catalog a presence without engaging it, but now he leans back with one absurdly long arm for handshakery and introductions. He eyeballs Rory and Liam with knowing, warm suspicion. "They're not giving you any trouble, are they?"
The resounding eyeshifting seems to indicate that okay, they might have been a little bit, but they are so awesome Shannon should obviously find that totally endearing. He settles in and looks for Judith; introducing her was probably not necessary, since she's much more a part of this than he is, for better or worse.