It's already a big-ass river with the border patrol cruising up and down the region in boats and trucks. The buoys are needlessly provocative, serve a purpose outside the purview of state authority, are ineffectual at any significant scale and thereby just trying to push people to even more dangerous routes without any actual impact on unauthorized crossings, are dangerous beyond what's visible, and are most likely ecologically harmful.
Honest people can disagree about the economic strain of unregulated migration, whether border states are getting the support they need from the Federal government, and who "deserves" what, but this is petty posturing and hurting people without making an actual policy difference. The notion that the state suffers overall from the inflow is just a racist dog whistle anyway.