When I enter a Bible reference in the Sermon Starter and am not careful to use one of the passage options presented on the drop-down menu, the guide defaults to whatever is at the top of the list. That turns out to be some topic. If I am not careful, then, I get a topical sermon starter.
I am glad there seem to be two sermon starter base templates: one for textual sermons and one for topical, but I think the options need to be separated so that I can type a passage and hit enter and get the guide to run on that passage. You could do that like you do with the search tool:

After I choose the option I want, the guide should only accept either textual or topical inputs.