Just because migrants came here without your permission doesn't mean they came here illegally. They're here legally. Otherwise, local authorities could have had them detained at an immigration processing center.
I swear, whether we're talking about an FBI raid on a former president or legal immigration, conservatives seem to have this problem of failing to realize that the law just isn't whatever the hell they think it is. The law is what's on the books and enforcement of the law is also further stipulated through criminal and administrative procedures. They call it the rule of law for a reason - so that people can't just use the justice system to suite their own political purposes. At that point it ceases to be the rule of law, and becomes the rule by men. And that doesn't usually work out too well.