But apparently that was deeply offensive to one guy in the team. I cleared probably 15 or 20 injuries off myself in that STF, just ignored that one critical because it didn't matter and I could clear it for free later, and was hounded the entire time. I thought about leaving that injury there forever in hopes of meeting him in another STF, but it was gone when I logged back in today.
Your situation is different.
The person you're quoting is speaking of people who enter an Elite with 4, 5, 6+ critical and Major injuries to their ship and refuse to heal themselves, seriously gimping their ability to be effective and to contribute in any way other than an aggro-generator and meat-shield.
It was kinda obvious from the Monty Python reference. However, if you have a critical injury in a single system that's nonessential to you, well...that's kind of Apples and Oranges, and you're still fine as you specify.