I don’t really agree. The borders are sieves at the moment. They need to be able to have checkpoints on this side of the border for that reason.
I don’t excuse the border patrol agents if they physically abused him, but I suspect from this account that he behaved stupidly and angered them for that reason.
If the borders WERE properly guarded, and if there weren’t millions of illegal aliens on the wrong side, many of them gang members and drug smugglers, this sort of thing wouldn’t be necessary. But in the circumstances, I don’t see what other choice there is.