Nations should have the ability to secure their borders. The issue is that, this isnt really a issue of a weak border. Its the side effects of American Imperialism in Central America and the fact that illegal immigration is a systematic issue that is being propped up and enabled by hundreds of corporations. There wouldnt be illegal immigration if you 100% had to be a legal citizen to work here.
Building a fence or wall is asinine because it doesnt address the problem as to why and how so many illegals come here in the first place. Republicans (and Democrats for that matter but mostly republicans) dont want want you asking "why", theyd rather just paint them all as "the Mexican Horde who want to to come to the greatest country on Earth"
First off, Trust and believe, those Guardsmen hate life. Operation Lonestar is a involuntary call up and they arent even being paid a real Active Duty salary for it.
Secondly, this isnt going to happen anyway. Due to Posse Comitatus, Active Duty troops cannot get involved in this in any meaningful way. Nor would any sitting president send them to oppose National Guard forces.
IF it truly got out of hand, Biden could just put the NG troops on title 10 status which puts them in Federal status, but that would be a trump level petty waste of resources and playing with peoples lives (tho the NG troops would get active duty pay then).