I guess those people mix up the Maxis side and the Richtofens side a bit, but I'm not completly sure bro.(like it's confirmed you need a timebomb for the wisp @ Maxis, but maybe not on Richtofens)
But you can get to the step where you'll need to get into infinity mode within 10 minutes, so I'll try if it is necessary to place 2 timebombs or only the one after the guillotine is charged to get in infinity mode.