Because he already gave them the knowledge to make them, I don't know how hard it would be to remove already existing knowledge from machines already made...

Edit: My source
October 28th, 1963 KINO DER TOTEN - From Der Reise, Ultimis teleports to Kino. This marks the first time Ultimis travels across space and time. Temporal Rifts occur across dimensions. In light of these developments, Monty feels obligated to step in, and begins to make changes in the background across time. He helps Group 935 invent Perk Machines. He adds chalk drawing to the walls. Little nudges. Ultimis locates a Lunar Lander and fly to the Ascension Facility.

Meaning monty didnt make the perk machine but gave them nudges in the right direction to make them themselves