You can be a boiling glob of hormones and still have manners. Not being a jerk about sex says nothing about Tim's orientation. But he was clearly written as being attracted to those women, and caring about them. Which doesn't discount the idea that he isn't straight, of course.
Again, do we know what he is yet?
And thanks for the info regarding him and Steph, folks. I thought they were sleeping together but the memory was fuzzy.