Staples in LVL beams: okay or to be avoided?
Don't worry about staples in a beam. (These are beams that can have 3/4" holes bored in them -- at appropriate sizes/spacings, of course -- so a puncture would mean nothing.)

I suspect your friend's story was more about the holding power of the plate than weakening the LVL.

(edited to remove "substantial" and replace with 3/4" -- thanks SP)