Ok so I’ve given it some more thought and you’re right. Manipulating the genes of only mutants wouldn’t make sense because there’s only one gene that causes “X-gene” yet he seemingly manipulated Storm’s whole genetic makeup. Once he deactivated her X gene she technically was no longer a mutant but he still was able to morph her back to normal. This suggests to me that his specific omega power is “genetic manipulation” This would differentiate him from Elixir who manipulates all biological life, but genetic manipulation is still a powerful ability that could have no upper limit so it would make sense.