Folks I think we got off the direction I was heading. I wanted to know if the author has asked for feedback as this one did, do you give them feedback?
Okay, back on track, then. He wants feedback but he is a space opera writer. If he is at the handwavium end of the spectrum, he's probably not that keen on science fact. You could ask if he wants it.
But, on a different note, why do you want to give it? To make the book better, to change it, or to enforce science into it? Is it for you or them?
If I got the note, all seriousness in place, it would depend on the tone. If it was the tone of your first post - nope. I'd mark you down as not my target audience and move on. But if it was a polite enquiry asking if I wanted to know why my fun space battle broke lots of laws of physics, I might want to know. Might. Depending on if there was an expectation to fix it. (You say he doesn't know gravity - perhaps he does, and finds it boring and wants more escapism.) so, I think, if I sent the feedback I'd start by asking would it be helpful. In case he's a particle physicist having fun on his day off...
Ps don't ever read my stuff. Your toes would curl in horror.