I refer to his involvement in Afghanistan. We may not have handed him cash directly -- he did not need it personally -- but we supported his organization and he worked directly to funnel that support to the mujahadden.
http://www.thesmokinggun.com/archive/binladen1.html
Using the same standard that is applied to evaluate Saddam's "links" to Al Queda, this relationship and common goal would be enough to have been touted as "proof" of a connection to a terrorist.