The burden of proof is on the government to prove that any violation of the Military Selective service Act was "knowing and willful". That's almost impossible without a public confession, signature on a registered letter, or testimony of an FBI agent who served an order or notice to register or report for induction.

According to the Federal Office of Personnel Management, only 1% of cases of nonregistrants adjudicated by OPM result in denial of Federal employment. Almost everyone who appealed a denial got their job restored:

https://www.govinfo.gov/content/pkg/FR-2024-02-07/pdf/2024-0...