I imagine part of the answer to this (as far as the reporters are concerned) may be that, since LE now has the gloves, it will be more credible and more impacting when LE/prosecution makes a statement about them and especially about whether it is blood/paint on them. Reporters may feel that at this point it is LE that needs to make that determination, not BB.
I agree, though, article comes across as quite cryptic, for no immediately apparent reason!
They have gone about as far as they can go, I guess (with the headline, the statement that BB uses this kind of gloves for painting, etc.) without taking the risk of looking not credible should it by chance happen that there is blood on there rather than paint.