Celtic most certainly had the option of declining their place. They chose not to. And yes, I do expect a club which got knocked out due to getting humped 6-1 not to go through because of a meaningless clerical error which had no effect on the result of the tie.
The only pathetic thing here is a club which lost 6-1 over 2 legs now being reinstated into the competition because of an administrative error which had no effect on the result of the tie.
Even if Celtic don't qualify it still means Legia are denied the potential to gain about £20 mil in prize funds for participating in the CL group stage.