Naw dude, that would’ve never worked for real. Ben’s Omnitrix has a bunch of failsafes to prevent it from being removed or to prevent Ben from dying, which would certainly include his arm being cut off. The second it was about to happen, The Omnitrix’s “Say No to Death” Failsafe would’ve kicked in and turned Ben into Diamondhead or Atomix or something, and those stupid-ass scissors would’ve done JACK SHIT. That Death Battle vid was completely loaded.