Rules Question: maintain an untenable position or course

I was re-reading the optional battle moves just now in preparation for my groups third session.  Since the first I've promised that in the future I'll allow the optional battle moves in the future so that we can try out slightly more complex, tactical combat.

there is a line, however, in the description of  maintain an untenable position or course that confuses me.

"When you maintain an untenable position or course,
roll+hard. On a 10+, you can hold it, and for 3 ticks you’ll come
under only incidental fire, even past 9:00. On a 7–9, you can
hold it, and for a tick you’ll come under only incidental fire.
Either way you can abandon it before your time is up to avoid
concentrated fire."

Emphasis mine.
This just doesn't make sense to me.  If you hit, you get a period of time (3 or 1 ticks) during which you only receive incidental rather than concentrated fire.  But you can give up your untenable position or course before that time is up to avoid concentrated fire... which you wouldn't be taking anyway.

What am I missing?

Nothing. It just means you can abandon the course early if you don't want to keep going down the path toward concentrated fire. That clause is just in there to say, "If you want, at any time, you could abandon your course. It's not like rolling for this makes you locked in to that course."