I never saw a reason to ship IshiTsuba outside of for Ishigami's happiness, but he will find an even greater happiness with Iino so it's all good. I'd have even taken him ending up with Osaragi or Kaguya before Tsubame personally.
This is easily the best one so far. I kind of edge out Kirisu over Asumi at gunpoint but it's going to be a tall order beating this route. Especially with this chapter. Everything about this chapter is just lovely.