Tangible progress can clearly be demonstrated in this type of...

Tangible progress can clearly be demonstrated in this type of project, and those building the airport have already built other airports which removes doubt as to whether or not they are capable of doing so. Additionally, building airports does not require fancy new technology to be developed, there is no doubt as to whether or not it is possible.

Your comparison is not only false in that progress is tangibly demonstrated, it is a non sequitur due to the lack of relevance in comparison.

With AGY there was a prototype which was never shown to work but they said did, and then what was supposed to be a working facility based on the prototype, which years behind schedule doesn't work any better than the failed prototype.

If no one had ever landed a plane or built an airport, and someone claimed they had built an airport capable of landing a plane despite attempts to do so failing, and then they built a larger airport which also did not successfully allow planes to land even years after completion and repeated attempts, your comparison would be valid.

I totally agree that rate of production is not the only metric of progress, I was one of the main people pointing this out in the AGY discussions two years ago when others were upset about it, but after enough time has passed, a complete lack of demonstrated progress does become a relevant concern.

Even if you don't think it is a concern, the reality exists that there has been zero demonstrated progress in over four years. When the mechanic says your car will be fixed in a week you don't care about zero demonstrated progress for a week or so, but after two weeks it's a concern and after a few months it's a huge issue and you would demand evidence of something being done.