"To determine whether a unit wounded by a Barrage weapon is allowed a cover save, and when determining Wound allocation, always assume the shot is coming from the center of the blast marker, instead of from the firing model." BRB; Pg 24, second bullet.
I can bold things too!
The line is fairly clear IMO, you only use the centre of the template for wound allocation and cover saves, but not for any other purpose - such as granting special rules as is the case here.
Lets do a thought experiment: say a unit had a special rule that if they took hits from a model within 12" they dealt the firing model a S4 hit. Would this always be triggered by barrage weapons?