Chromium is not Chrome. Switching from Chrome to Chromium is still leaving Chrome.
Whether or not Chromium or Firefox are more to your liking is another matter, and whether or not switching to Chromium accomplishes what you want to accomplish by leaving Chrome is another matter.
Not really, think of Chromium as a developer version of chrome. It may be open source but it still maintained by Google. Only alternative shift to Firefox.
You can change Chromium but you cannot change Chrome. The majority of Chrome is Chromium, but there are parts of Chrome that are not Chromium. Particularly the branding. Furthermore if you're actually forking Chromium like suggested and taking it in another direction to assuage any grievances you might have with Chrome, then you have certainly "left Chrome".
I was not recommending that anybody switch from Chrome to Chromium. Personally I do not find that Chromium fixes what I consider broken about Chrome, which is what I was alluding to when I said "whether or not switching to Chromium accomplishes what you want to accomplish by leaving Chrome is another matter." The negative reaction I received for that post makes me think people believe I was recommending Chromium. I do not; I recommend Firefox.
Whether or not Chromium or Firefox are more to your liking is another matter, and whether or not switching to Chromium accomplishes what you want to accomplish by leaving Chrome is another matter.