Sounds like Mexico can just take down most of this thing.
Edit: As a US citizen, I support Mexico's immigration services to detain any Texas construction workers that illegally cross the border to service this thing.
I also would support the governor of this region of Mexico to put these construction workers on a bus and drop them deep in the heart of Mexico somewhere.
Probably the only reason Mexico hasn't already pulled it out is because they don't want to waste money that they know will never be reimbursed to them.
Maybe the US will take it down and bill Texas themselves.
They should just be drowned. That's the purpose for this barrier, so I think it'd be fair to drown anyone working to construct it. (I don't condone drowning the workers, but the workers should stand up against their employers due to drowning risk. If they don't listen, maybe they should have an "accident" and "drown" instead and the workers take control.)