I don’t think so, but the Northern Vietnamese generated a bunch of FUD about it. Gross simplification, but essentially committed anti-war activists or others opposed to the US campaign (including foreign powers) would sometimes accept the Northern Vietnamese account of humane treatment as fact.

What Brent did was get concrete intelligence about exactly who was still alive and in prison, so that families could know their relatives were still alive and N. Vietnam could be publicly held to account for their survival at least.