I don't know whether it would be a good thing or a bad thing if Tsukishima fought Kenpachi. Kenpachi would get slashed just because he felt like it, or Tsukishima would pull a clever trick like he did with Byakuya. But would Kenpachi just indiscriminately fight Tsukishima either way just because he feels like it, or would he start attacking the good guys like every one else Tsukishima slashes?
But more importantly, I think these past 2 chapters have proven that Tsuki/Ginjou are captain-level, or slightly beyond that (assuming Ginjou's the stronger one), while the other fullbringers are vice captain level.