Thomas Massie is a terrible lawmaker, and I'm glad to see him go, but his articles of impeachment against Hegseth are devastating and self-evident. It is to the current House's great shame that it failed.
Under normal circumstances, even a single one of these charges would result in the secretary's resignation or firing. But under the current president, the only grounds for that are disloyalty (to him). War crimes are just part of the job.
Of course, the next congress (seated in just a few weeks) is free to vote on the same charges.
Although impeachment has some of the trappings of a criminal process, it is not one, and there's no protection against double jeopardy. When and on what grounds to impeach is entirely up to the House, and whether to convict entirely up to the Senate.