I dont consider this as cheat because its part of the game. Like saying developer 1 is cheat 
If your skillful enough to do it then I got no problems with it
Still there is difference between legal groundstrafe and illegal one
legal one is ONLY made with basic bind command which is:
bind mwheelup +duckAnd mostly illegal ones is made by using cheat; kzh gstrafe, xhack gstrafe and scripts
With scripts I mean commands where you control when your character ducks with "wait 30;" "alias;" and toggle commands.
I'll watch this demo this evening