In view of the walkover, I do feel that it is unfair for a player to get 乙级 this way.
What I recommend is this, in order for a player to get promoted to 乙级, the player must achieve 1 win (excluding those achieved by walkover) in the knockout round.
Example, Player A gets into the semi final through walkover. Player A will not get 乙级 but still have to win in the semi final.
I hope SIXGA will seriously consider this recommendation as I feel last minute pull out is inevitable in a competition which last for weeks.