But teleporting Mortarion? Dude. You can't even quote a fact correctly. You read it how you desire, replace Mortarion in that quote with anyone else, and it is a metaphor.
Can you provide me with GW's quote (or indeed quote your own sources, in particular for halo) that states that their game is anything less than canon?
The storyline is the canon. If Spartan PC dies, you reload until you continue in the story. Multiplayer certainly doesn't count. The mechanics of the game are there to tell a story in single player. Otherwise are you going to include Dawn of War? I can make a single battle company produce more than an entire chapters worth of marines. Thats in single player, as well though.
I think you may be experiencing difficulties with understanding how varying levels of canon work within a single continuity, and then comparing it with another IP altogether that also possesses varying levels of canon within its mythos.
The very fact that you are referencing Mortation teleporting which is entirely left to interpretation, of which you then have concluded he has not demonstrates your extremely fixated opinion as being correct above all others (save for those who agree with you).
What is canon concerning the Halo games is the campaign storyline and all feats done within it, the main character dying obviously is not canon as then the ending of the storyline would not be achieved.
All it takes is a bit of...perception to understand, perhaps you should take up reading some classic literature, it may help you to understand varying paradigms.