When Deinterlacing, app will not maintain input FPS

If I de-interlace, I’d like to be able to keep my source frame rate (29.97 in my case) and not get the doubled field rate (59.94) as my only option. The current setup can stay default, I just don’t need the extra frames and want an easy way to keep it 29.97.

(Not looking for arguments over whether 59.94 looks “better.” 29.97 is fine for me.)

I am aware of this:

But that’s a workaround. It should just be an option in the Frame Rate menu.