On the issue of the age of the universe I have no problem with those that want to be believe in the scientific view concerning the age of the universe.
I do leave open the possibility that the Universe was created in an "Old State", and it is much younger than it actually appears, although it does not fit into my own personal interpretation of Tehillim/Psalms chapter 19:2 and 111:7.
I do not believe the current theories of evolution offered, adequately explain how the world developed to what we see today.
This is purely on the science level.
But what bothers me about R. Natan Slifkin is not his scientific views, but rather how he explains the Biblical text of Breishit/Genesis Ch. 1 and 2 in light of his scientific views and its implications for Shmot/Exodus Chapter 31 verses 13-17
I would like to suggest at least 2 better Old Age of the Universe interpretations of Breishit/Genesis Ch. 1 and 2
see
http://www.vilnagaon.org/book/science-creationdays2.html