I don't think anyone here has made that claim.
As for importance to the team, well yes Tkachuk is one of our key players. Arguably he's currently our best player. Much like McDavid is your best player. Of course, that says nothing to the skill level of each of those individuals as clearly McDavid is the more skilled player of the two, and anyone stating otherwise isn't being honest. That doesn't diminish their individual importance to their respective teams.
My issue with the so-called "code" that keeps being thrown around is that there is no expectation for a player to have to fight to respond to a clean legal open ice hit. Clean, in the sense that no penalty was called, that the NHL reviews and dismisses claims that illegal hits were made.
In the Giordano case, while it was nearly an illegal play, the referees were letting minor things go all night. Yes, he had his leg out and ankle to ankle contact appears to have been made. Also appears that he stuck his arm out too, which is why someone lost a glove. The "almost kneed him" argument is invalid because he didn't do it, whether or not there is an indication that this may be a pattern.
Be angry with the referees for not calling things consistent that night, not Giordano for almost/maybe interfering or tripping McDavid. There isn't a code that applies here, just the rulebook.