It's strange I have had a couple of sets with woodworm holes in the base of the cabinet only. A Philips Style 70 and a 23" Bush. Both sets had a lot of activity but only in the ply base.. No where as bad as your set though, both were saveable with treatment and filling the holes.
Are you going to treat the rest of the cabinet with killer?
I stripped both sets out completely and soaked the inside of the cabinet rolling it around to get it into all the nooks and crannies.
On advice from here I put one of the cabinets in a chest freezer for a week just to be sure.
My concern was that they were dormant in the other wood and would re occur at some point. Even now a year or so later I am keeping an eye on them for any new holes.