No we can't. If it's not molecules, it's not water, and there's nothing here to indicate whether the hydrogen and oxygen are found bound together.
While water will break down at high temperatures I would find it surprising that 1st and 3rd most common elements in the whole universe, that readily combine to form water would not result in substantial amounts of water.
It's probably like saying we shouldn't find H2 because "nothing says they are found bound together"
No, I never said it is a fact, it is, as you pointed, a conjecture, and I provided a source (ok, wikipedia) for the amount of water in the universe
If you or him knows of a reason for why the most common elements in the universe that combine easily wouldn't result in an abundance of their combination I'm all ears.
(Which doesn't mean the amount of water is going to be near the amount of H2 or just the amount of Hydrogen present in the stars)
I would expect that in planet formation situations
http://physicsworld.com/cws/article/news/2013/mar/13/cold-hy...
http://www.popsci.com/technology/article/2011-06/herschel-sp...