I'd say it's more of a general empathy.
She obviously has some form of food out there, considering she was able to spin as much web(?) as she did. I cannot even conceive how something like that would be compatible with human DNA, so breeding wouldn't be a need, and if it was, why Thom in particular. There were the two other crewmates whose pods failed or were broken to 'save' them by Thom when he woke up the first time
if she needed DNA. They weren't even eaten either, just dead.
I can think of no reason other than either loneliness or empathy. Maybe his mental state is painful, since she's apparently psychic or mind-melded or whatever, and can effect her so, so she's trying to quiet him without murder.
Or she's just nice.
Or she's actually Greta, and she was mutated by the radiation around the station from being there so long and she actually knows Thom.
It's hard to tell from how quickly it ended.