I believe the accepted timeline here is that Apple did try to license the tech before "infringing", Masimo asked for ridiculous terms, wouldn't really negotiate, and then Apple looked at the patents, realized the patents probably shouldn't have been granted in the first place (as
@TonJay and
@spazzcat pointed out) and so decided to risk it. They got a lot of the patents thrown out, but not all of them.
I'm not saying that what Apple did was the correct/moral decision, but this isn't a case of Masimo asking for unreasonable terms because Apple "infringed", it's a case of Apple "infringing" because the patent holder wouldn't license with reasonable terms.