Is my understanding correct that Trump (executive branch) currently has control of both congress and the senate via Republican majority? If so, what hope is there for a federal judge to rule reasonably on this case?
That's not how the US system is supposed to work.
The constitution doesn't even mention political parties,
and there were none in the US for the first 20 years or so.
The executive, legislative, and judicial branches are independent and constitute a system of checks and balances.
No executive "controls" congress or the courts, nor do any of the branches have control over the other two.
As for Republican control of the congress,
that can lead to cooperation between the executive and legislative branches,
but history shows that congress does what it wants,
not necessarily the will of the executive.
The courts are even more independent.
Judges are non-partisan,
and supreme court justices appointed by a president of one party and confirmed by a senate with a majority of the same party can and have ruled against the president that appointed them.
For example,
in ruling against president Richard Nixon in United States v. Nixon,
Chief Justice Warren Burger wrote the opinion for a unanimous court,
had been a lifelong Republican before his appointment to the court by Republican president Dwight D. Eisenhower.
I think it will be interesting to see how Trump's justices rule on this sort of thing; I suspect that they are not actually as beholden to him as people are inclined to think. They got into this to oppress minorities (they were pretty much chosen off a list of judges who were seen as reliable (in a Republican sense) on abortion and voting rights and so on), but potentially not to wholesale disassemble democracy in the US, and there's very little that Trump can do to them. I think he may find them less cooperative than he's hoping.
