Elite nailed it on the head. Right before you enter the States, if you're a non-Murican the first thing CPB agents aka Immigration officers (and no, they are not the same as TSA, who are useless as shit) ask is "What is your purpose". For minimal fuss, keep it short and simple. So Kiara should've just kept it to "visiting friends", specially if she's on a tourist visa. Any mention of work or business triggers a bloodhound like response from CPB agents when you don't have a business travel or work visa (one is for meetings, scouting locations, consulting etc no longer than a few days to weeks,the other is more for yes I will be here for a looooong time and I have the paperwork to prove I am needed). They are meant to be zealous when it comes to this kind of thing becuse entering the US on false pretenses/illegal work is a big nono and has been the biggest complaint of every "muh jobs are being taken by da mexicans" lazy fuck who won't work the fields.
So yea, when Kiara said "work friends" it set something off for the agent. Now, she could have wrapped it also as "this is a destination vacation with work friends", that might help, might not. Again, keep it simple. The agent grilling her was likely trying to figure out if her "visiting work friends" is just that, visiting or will she be doing things with her work friends that would be considered work since she's a Vtuber and/or if that invalidates her visa. With technicalities, since she's a Vtuber/Youtuber, you could say streaming within the US is her doing work, thus its illegal. It can also be argued, that its just vlogging/chatting kinda deal. Work legalese gets confusing and grey when it comes to Youtubers and media influencers (but not film production or produce picking).
Not like it really matters per se. It's not uncommon for aliens in the US to stumble over something so minute and small that they're not suppose to do but it's such a blip in all the other immigration stuff, everyone kinda shrugs unless the CPB agent is having a bad day and decides to be a hardass. If the agent Kiara ran into is a stickler, could've easily pulled up her channel, see what she's been up to, make a note on her immigration file and viola, she's now on a list. Ofc, Kiara could've have easily picked up a business travel visa, and for the agent, things don't really line up so the grilling was for more info to be able to connect the dots to again, determine if Kiara's entering for the right, wrong, or muddy reasons.
Oh and the touristy entry points actually do give a shit. Just that when you have hundreds of tourists with either their kids or elders behind em, you kinda have to just put on a dead fish expression and get to interviewing and stamping. In fact, showing up at those entry points without being in some kind of tour group or holiday plan would set off some alarms for em. Sometimes for solo travellers, its best to either come through the really busy and common thoroughfares (so like CA if you are coming from Asia/Oceania, NY if EU) than landing in a touristy or out of the way state.
Oh and for clarity:
TSA =/= CBP
TSA = glorified Federal traffic cops who are suppose to stop Ahmad from taking over the plane
CBP = actual Federal Agents who try to catch Ahmad and Juan before they cross the border into the US
One is very inept at their jobs, the other occasionally doesn't fuck up
