This is a compelling idea but almost certainly not true. WW is often very sensible in the world building and especially when it comes to HERO and Bramon Xanthe. They are ruthless but sensible. So this seems... unlikely.
Firstly, it'd make no sense mathematically speaking. Level fives are rare, powerful, and essentially the main thing that HERO as an organization relies on. The rest are canon-fodder, or damn near. Any level five is someone that's managed to reach that level (which is not guaranteed even with the serum. Few reach level four, and the serum can fail. Ella got extremely lucky, it's supposed to be tailored. Which Xanthe tells you when discussing methods of evolution and explaining why yours was kind of a wild card) and has experience with their power and is an asset to the organization (There are only 12 level fives, remember) that's basically priceless.
Sacrificing a level 5 to make a new one (and potentially failing!) is like trading in a winning lottery ticket for another that's PROBABLY going to win and might win less even if it does.
Secondly, exposure to SUPERHUMAN material does not seem to have the same effect. Deryl was fully monsterified at the time.
