even to the point where some are saying "it's obvious someone else seated the other kid" even though in the video he said "I didn't get a good look at his shirt" implying he seated them.

That's just a bad assumption. The conversation flowed like this, obviously with more complexity:

Woman: That boy is wearing athletic stuff too, see? Oh He's gone now, we can't see him anymore.

Man: I didn't get a good look at his shirt.

Why on earth are you assuming he's implying he seated them when the flow of the conversation does not imply that in the least? The kid is gone now, and the woman's argument was "Look, he's wearing athletic stuff too", which means if the man didn't see the kid his response of "I didn't get a good look" is exactly what he'd give. If the kid was still right there you'd be right, but the kid is already gone and the context at the time the man says he didn't get a good look is far more fitting if he didn't seat them because of that context.

There is absolutely nothing in the video that implies he seated the other kid. The place should have accommodated for them at that point, but we don't know the rules the restaurant has and how much the other people working there care, for all we know the guy is trying his best to get them to leave because someone else that works there already made the decision and he either has to just go through with it or has to back up his coworkers or risk trouble at his work. If he did anything in the video that implies HE did anything wrong and there is no potential it wasn't someone else who worked there that sparked the issue, that's different, but from the video alone we have no context giving anything he specifically did wrong, because the simplest context of "his boss told him he had to do this" instantly explains this away. It doesn't matter if he "stands against racism" by defying his boss in that context, because the boss would still kick them out AND now fire the man.

People are defending the guy because people like you make false assumptions, again nothing in the video alone proves this guy did anything by his choice alone. Maybe he is the only one doing something wrong, and his coworkers are fully uninvolved, but we'd need more context to find out.