I appreciate that you acknowledge that racism and xenophobia taint the arguments you're making, even if you yourself are not racist or xenophobic. It's hard to stand up for a view when it is held by people who are widely reviled, and I suspect that courage is something our country needs more of.
However, I think the examples I provided compellingly demonstrate that issues of legality do not sit at the core of the anti-immigration sentiment in the US. In particular, an overwhelming concern for the sanctity of law would likely not motivate one to demand that a sitting judge recuse themselves because of their ancestry. Nor can it have motivated anti-refugee sentiment.
More broadly, the argument about rule of law does not have good explanatory power for the actions and statements of those who make it. It does not explain opposition to open borders, or to more expansive visa programs, which of course could both be made law with comparative ease. And it seems obvious to me that anti-immigrant militias like the Minutemen represent the height of contempt for the rule of law, but somehow find a warm reception among those who advance the very argument that you do.
Does this mean that nobody legitimately cares about the legality of immigrants? Of course not. It is possible that a broad coalition of people simply happen to agree on this wide range of narrow topics that have nothing whatsoever to do with race or ancestry. But Occam's razor suggests that the simpler argument is the better one: that duplicity and political convenience are at play.
Specifically, I suspect that the broader anti-immigrant movement in the US believes it has a winner of an argument in this one despite its lack of policy prescriptions. As a result this argument-- the one you make-- often gets advanced as a fig leaf for those "other" viewpoints. Which leaves you in the awkward position of carrying water for some truly despicable people, whatever your own views are.