Note that the trees in question are Coastal Redwoods, not Giant Sequoias, in Big Basin, maybe five miles from the coast, near sea level. They are TALL trees, with some over 300 feet tall.
The Giant Sequoias in the article you linked are in the Sierra Nevada mountains, at a few thousand feet elevation and a couple hundred miles from the coast. They are MASSIVE trees, truly awe-inspiring, a bit shorter than the Coastal Redwoods but with trunks 30 feet across.
I don't think Coastal Redwoods have any trouble propagating or germinating. I have one in my back yard. Apparently they can be germinated in tap water. https://www.treeseedonline.com/blog/germination-of-coast-red...
Giant Sequoias, on the other hand, I view as truly irreplaceable. Some are over 3,000 years old. I hope we can protect them as long as possible.
The two species are cousins, but it's important to differentiate between the two.