You can make an argument for building the TMT. You can make an argument for not building it. But there's no argument I can think of to support what the state is doing. The first time that the TMT tried to start construction, back in 2015, a fairly small group of protestors was able to halt construction by standing in the road and blocking vehicles. The police would come up the mountain, stand around for about 5 hours waiting for instructions from sea level, arrest perhaps 5 percent of the protestors, which did not allow the contruction vehicles to pass, and then everyone would drive down the hill again. The protestors built a small, unpermitted building (illegally) near the point where they wanted to block the road, and the state made no effort to prevent them from doing so. The protestors would pile stones in the access road to the TMT site, and then claim the pile of stones was a sacred alter. The state would remove the alters after a very long period of dithering. So the protestors could build, in a few hours, a physical obstruction that the state would take days or weeks to move. In general, the state made about 1% of the effort that would have been required to allow the TMT construction vehicles to reach the site.
This time, the group of protestors is far larger. They have camped out at a place that is more convenient for them, logistically. Unlike the situation in 2015, they have shut down all of the observatories on Mauna Kea. If the state made 1% of the required effort to open the road in 2015, this year they are making 0.01% of the required effort. The police drive up, hug the various protestors for a few hours, join the protestors in prayer. Then drive back down the mountain after having no effect at all. Yesterday, they made some token "arrests" which involved issuing misdemeanor citations. Some of the persons who had been escorted away from the road blockage immediately returned to block the road after the citation was issued.
This is a wonderful example of asymmetric warfare. At first glance it looks like the state is the powerful entity, but the protestors have all sorts of levers they really haven't started using yet. How long will the University of California remain a member of the TMT collaboration once UC students start having sit ins? The University of Hawaii's Hawaiian Studies Program (most of the members of which oppose the TMT) is far stronger politically than its Astronomy Department - how long will it be before student protestors force the University of Hawaii to drop out of the project? How long until protestors on other Hawaiian islands start blocking state facilities?
There were at least 1000 protestors involved with blocking the road yesterday; some estimates put the number at 2000. There is no facility on the island of Hawaii where that many people could be incarcerated. And there is no indication that the state is willing to incarcerate anyone who is blocking the road. If the state actually makes a serious effort to open the road for the construction vehicles, there will be many consecutive days where the television coverage will show weeping, elderly ladies in mumus being hauled away to sea level. Day after day after day. There is absolutely no reason to believe that the state is willing to do that, and recent history shows that they will not. Even if the state had the nerve to forcefully open the road, for how many weeks could that go on before some member of the TMT collaboration decided that TMT is not worth the black eye Astronomy is getting in the court of public opinion?
In addition to blocking the road, the anti-TMT protestors are still filing frivolous lawsuits to stop construction. I think they would be wiser to drop their legal efforts and just let the current sutuation play out. If they get a court order to stop construction (as they did in 2015), the state could still pretend that it would have eventually cleared the road and allowed construction to begin. The TMT management might be deluded enough to think they could still build on Mauna Kea. But if the protestors drop the lawsuits, and just allow it to become crystal clear that the state won't clear the road and get the construction equipment to the site, then everyone will finally know that the TMT won't get built on Mauna Kea.
As I said, I'm a TMT supporter. But sometimes you have to admit defeat and go on to plan B.