It's relevant because they aren't just VC bros or Saudis. It's just 670k. I'm not sure why you're so worked up about it or why you think Kagi shouldn't get additional funding.
Public trading means clear protocol for ROI and it allows to have many small investors who can have as little say as you specify (non voting shares etc). Comes with requirement for a lot of documentation and transparency too. So accountability. If business I like wants to grow and needs money this is the route I want it to take
You don't need to organize fundraising events etc you just do your thing and if you do it well you get extra money.
But of course it is all assuming Kagi cannot profit enough from is users. Which apparently it cannot.