(edited out pics to save band width)
I clicked on the link you provided. I think you forgot to include this post:
The reason they have Glock 19's is because that is what the Iraqis are issued. SF spends most of its time co-located with indigenous forces which has always been their mission. Delta and SF are not the same thing. The majority of SF still has Beretta's. Delta has had the same issues with Glock 22's and lights that many police units have had.
and this which is the reply to the quote above
Oh yes, most SF pics still show guys with Berettas, no doubt. I posted these pics as they are the exception, not the rule.
So I guess they do use Glocks but are the minority due to reliability issues and geographic locations as evident by the link REAPER so graciously provided.