So obviously this is a funny line. It's one of the earliest instances of Sissel saying something both very weird and disarmingly sincere, even if he's mostly parroting Ray from earlier.
But what also catches my interest is his phrasing: he doesn't say "I don't want to leave her there," he says he's "not the type" to leave her there. Rather than stating his wants, he asserts this as part of his identity. Which, as he realizes not long after this, is something he doesn't have much of at the moment.
Obviously, one could read this as a bit of Sissel's personality shining through, as it does in some other bits of dialogue. After all, later in the story, he makes the choice to keep saving people even when it lends him no benefit.
...But that's only after some character development. As we learn towards the end, in a version of events where Ray isn't being such a mysterious tutorial guide, Sissel doesn't choose to help Lynne at all. And before this, when he was alive, he wasn't someone with the means to help anyone out much, regardless of his desires.
That said, the face he's wearing isn't his own. And that face is also closely entwined with his memories, a person he knew for a long time.
Okay, you might be saying, so maybe he said this because he thought Yomiel was "that type." But why would he think that? Yomiel spent most of Sissel's life in an agonized, lonely state of depression and anger. He probably wasn't doing much helping anyone. In fact, he even caused Lynne's current predicament.
Why would Sissel subconsciously think of Yomiel as "the type" to reach out and help a lone, desperate soul with no means to help themselves?