This is what makes it such a great red herring, there's a solid explanation behind it.
I honestly think the best piece of evidence comes from episode 3 and 2 though, where 02 has a brief monologue at the very end after piloting with Mitsuru and Hachi describes a fundamentally important aspect of the nature of compatibility respectively.
For the former, in her monologue she said that Mitsuru isn't cut out to be her darling, just like she thought. Before looking at Hiro and saying to herself that only Hiro is her darling.
The scene implies there is actually something very special and unique about Hiro for her, if she just wanted another corpse she could have stick with cunts like Mitsuru.
For the latter, Hach points out that for two partners to be compatible they have to trust each other. Implying that 02 and Hiro's compatibility of 98%, or so, means they trust each other on nigh every level. They'd willingly put their lives in the other's hands. Which jars considerably with 02 as a malicious schemer.