I disagree... I argue that computer science (which is really information science) is indeed a real science.

With difficulty!

Just keeping up with the stuff I should keep up with for my professional use is already impossible: the sub-sub-sub-sub field I work in sees hundreds if not thousands of publications every year. Just being aware that they exist is not possible, let alone read all of them.

But I am curious and interested in a lot more, in more general sub fields related to my subsubsubsub field but also in entirely different disciplines. All one can hope for is getting a tiny glimpse.
But then, whether or not this is frustrating depends on why one wants to do it and what the aim is. Since personally my main interest is simply to figure new stuff out, I am not really too bothered about there being so much else that I did not figure out yet. Rather, enjoy the journey!

PS: I would have to disagree with your ex. Of course it depends on the concrete of field within computer science, but in a lot of those fields, science can be done, even if engineering can be done as well!
But take theory of computation, discrete mathematics, graph theory, category theory, various kinds of machine learning (gaussian processes, beyesian nets, variational inference ...) -- all these can be done as proper science, sometimes even with proper proofs and sometimes be even relevant for the engineers!

Go to colloquims, where professors present their latest research. Saw one a couple weeks ago that blew my mind. A professor used light refraction to identify particles in ocean water. It was as accurate as lab analysis.