Skepticism could be constructive. Most of time people just want to improve some novel idea in question format. If someone really do not care about it they would not even bother to raise a question.
I do want to raise my hand about how the sails is going to avoid space objects (meteoroid, space dusts... visible, non-visible, or even dark matters) given its large surface.
Outside of Earth orbit, space objects become incredibly rare, and outside the solar system they are rarer still. There are much bigger problems to worry about, believe me.
By the way, dark matter is likely passing through your body right now. It's effects can only be seen on the scale of galaxies.
