That's because he is. Take a look at the articles listed on his website.
Science can't tell us so far what really exists. It can only predict experiments. To put it in more common terms, "is the wave function real or not?", or "do quantum fields really exist, or are just elegant mathematical abstractions for explaining experiments?"
Or as others say "shut up and calculate".
Your "only" here makes it seem like predicting experiments is a narrow thing. It's not. All of the modern technologies we have--including the computers we're all using to post here--are based on science "predicting experiments"--but the "experiments" are things like building computers, or the Internet, or the GPS system. The fact that all those things work exactly as our science predicts makes it very hard to view that science as "only predicting experiments". It's telling us how to use real things to build real technologies that have real impacts on people's lives.
A religious person - if not honest enough to simply say "existence of God is an axiom and cannot be derived from reason alone" - uses the very predictions of experiments to reason God into existence: everything that exists has a cause; universe exists; therefore universe has a cause.
These are also not axiomatically accepted features either (except perhaps in the sense that they are in relation to the empirical sciences, as science presupposes their existence).
How do any of these things allow you to derive knowledge of God's existence?
If it were so, God's existence would be just another scientific fact.
Of course, the classical definition of "science" is more expansive, including what would be the most general science - metaphysics - so in that sense, yes, you can say the existence of God is a "scientific fact". (God here is self-subsisting being, not some ridiculous "sky fairy" straw man of New Atheist imagination.)
Change is not presupposed by science. Various experiences/models of change are described by science, which is not the same thing at all.
There are block universe interpretations of cosmology which do not require change.
If you redefine God to mean "fundamental assumptions of the universe", its existence becomes tautological. But that is not what most people mean (including the author of the article we're commenting on) when they say "God".
That's the popular definition of the word "real".
But this article is about the philosophical meaning of the word "real". And from that viewpoint science hasn't delivered yet, science doesn't know yet what "really exists out there", it can only predict how that thing behaves in experiments.
If the philosophical meaning of "real" admits that computers, the Internet, and the GPS system are real, then I don't see what grounds it has for rejecting that things like transistors and electrons and other such underlying things are real as well, since transistors and electrons and other such underlying things are what we build computers, the Internet, and the GPS system out of.
If the philosophical meaning of "real" casts doubt on whether computers, the Internet, and the GPS system are "real", then why should we care about it?
> from that viewpoint science hasn't delivered yet
If science hasn't, then neither has anything else.
the question is about what does fundamentally exist, not what you perceive.
do particles exist or not? is it all just in your imagination because you are a "brain in a vat?"
by saying these SCIENTIFIC questions are trivial to answer because you can hold a GPS receiver in your hand is to completly misunderstand what is being discussed here
nobody said something else deliverd on this question. but neither did science
Only inasmuch as nothing can tell us what "really" exists. By any practical definitions of any of the words in that sentence science is the best way of determining what exists.