Or no one had use holographic bullets (or just plain old bullets) on a Borg recently
. The Borg personal body shield doesn't work against everything, just the last dozen things used against them, which is why Worf can assault a Borg with a metal cutting weapon and have it work.
In the entirety of Borg history, while raiding some primitive planet for drones, no one ever used a knife or a sword on a Borg before?
Of course someone did, Worf's weapon worked because no one had used one that day.
The Borg shield can't do everything at the same time.
The tommy-gun worked because the Borg Collective had never been shot at with a tommy-gun ... Surely anyone with working brain can understand that?
Have a working brain and no, that makes absolutely no sense at all.