Well they were talking about historical definitions and I think maybe they give the source or at least Shishida gave it somewhere in another article. He is a bit of a budo historian. I'll check later.
Stalemate is always an unfavorable situation but you can see how that would be called harmonized energy. I also seem to recall the caveat that the to in stalemate were masters of their art.
Shishida discusses aiki on pp. 311 - 313 of his book 武道の教育力. There was an earlier discussion on aiki where I quoted the whole passage. Josh Reyer translated it.