Ahhh, the trustworthy test. Sounds like the same type of test that Trump plans to use in his hiring process. Coincidence? I think not. All part of the fascist playbook.

How unsafe is it? I’ve not seen any crash test results.

Actually, a few mm/sec is quite a lot. That could easily be more than enough to deflect an asteroid from hitting earth. That few mm/sec will accumulate over the time it takes the asteroid to travel six million miles.