It wasn’t just the sheet, but the pillowcases as well. Had he used the sheet, then why the pillowcases?
I don’t think Shanann was making much, if any money, with her MLM business. On the whole, most people don’t turn much of a profit at all. If anything, I think this could have made their financial situation, even more dire.
I think it’s more likely that there was some other motive, or a combination of them, that led to this. I think financial strain, discovery of his affairs, her threatening to divorce him, or him selfishly looking to move on from family life, are more likely motives than a sexual escapade gone awry.
Say it was something sexual concerned with choking, then why not try to save her by calling 911? Why murder the kids? JMO
Edit* I do think that if that choking story from his supposed AP is true, then he may have used this method on his family, simply because he was comfortable with it.