I don't think it would be bad at all to rescind unionization of federal employees.
There is nothing like having a disciplinary problem with an employee that cannot be addressed without seeking legal counsel first. Even if the boss does not want to punish the employee, but only to make clear that there are certain legal boundaries that govern both boss and employee. The unions complicate everything needlessly, and some employees are very prone to run off to complain to the union at the slightest problem.
Unions can be a pain, but they can also be useful. Many years ago I was a shop steward for almost a decade. We would have employees coming to the Grievance Committee want us to file a grievance. After the worker explained the problem, we would go over the contract with them and explain why the remedy to their complaint was not there. One complaint was that the personnel director had a large Playboy pinup as the first thing you saw as you entered his office. The secretaries didn’t like it but the contract didn’t cover it. I went to management and after a talk with them they ordered personnel director to remove the pinup. In another instance management was complaining about an especially incompetent employee. I said, “Well, if you keep them after the 90 day probation period, then we have to represent them, even if we agree with you.” After that, several new employees did not work past the 90 day period. Less trouble for everyone.