That would be a stretch because merely having them speak to media isn't prohibited. In this case I think they would be completely in the clear unless something happened behind the scenes. Everything about his speech suggested that he was self-confident and assured in what he was saying. You would have to show that Ukraine had coerced or humiliated the prisoners or treated them inhumanely. If they simply asked, "Would you like to speak to the media and tell your people what is happening" and they agreed, I can't imagine any charges being brought.
Now on the other hand, the videos that have been shown of POWs (on both sides) being hit, mocked, insulted, or forced by their captors to repeat humiliating things are definitely clear violations. I don't think they'll ever proceed to charges against either Ukraine or Russia though because 10,000 worse war crimes happen in every war and it seems only the most extreme ever get followed through on.