As someone who is keen on astronomy, I am of course keen on the Thirty Meter telescope myself. And I've heard those arguments of the astronomers, about how it is an ideal site for astronomy, about the value of the astronomy that can be done with this telescope and so on. But I've also heard the other side too.
There are many telescopes on the summit already, so it's not like they are saying not to build telescopes at all up there.
SIZE OF THE PROPOSED TELESCOPE
What you might not realize at first is quite how huge it is - it's difficult to get a sense of scale from the images:
It's higher than the Niagara falls.