> Let's imagine that tomorrow I come up with a magical super-reliable method of interviewing, which works better for most jobs than existing specific methods.
If you can demonstrate this is the case for the specific jobs where you want to apply it, you will then have no problem, even if it has a disproportionate negative impact on a protected class.
Only in the same sense that an unjustly accused person will "have no problem" as long as they're actually innocent. In practice, they do have a problem. Firms are afraid of using IQ tests and being the first against the wall.
If you can demonstrate this is the case for the specific jobs where you want to apply it, you will then have no problem, even if it has a disproportionate negative impact on a protected class.