Actually there are no grommets ....
But it is padded and definitely has some insulating value in practice - lying in my bunk and reaching around behind the curtain I have at times felt a very significant temperature difference (more than 10 to 15 degrees)
This the one we're talking about?
"The lightweight superinsulator for warmth and protection. Made of same materials developed for NASA/Apollo space missions. Reflects and retains up to 90% of radiated body heat. Compact, durable, flexible even in sub-freezing temperature. Windproof, waterproof, grommets in all corners easy to clean, just wipe off dirt, fade resistant colors, full edge binding, radar reflective material. Measures 82" x 50". Inside colors may vary."
That's from the site that you linked.
Did you get a defective one without the grommets?