Yes -- state agencies (licensure, regulatory, etc.) have no jurisdiction over federal facilities/employees. It's not about the setting (inpatient vs. outpatient), it's about who the employer is.
For that matter, the federal government could decide that it didn't require its nurses (or other professionals) to be licensed at all, and the states couldn't tell them otherwise -- but they have decided that their standard is "as long as you have A state license, from any state, not necessarily the state you're physically in." Same for physicians, PTs, etc.