As opposed to a destabilized US? Which is exactly what they're going to get if they allow this invasion to continue unabated, and ignore the vast majority of actual citizens.
I know DC can be stupid, but there's something afoot, there's got to be for them to ignore the demands of over 200 million Americans in favor of a foreign 3rd world nation with just over 100 million.
And thats the nub, which ever way he goes your President is going to have to bite the bullet.
I would go for stability in America at the expense of Mexico, but maybe he feels with a little tinkering he may be able to have both.
Like I said I am not an expert in this area.