Forester here and I'm going to go ahead and call bullshit on this post for a few reasons.
Redwoods are cool weather high humidity trees, LA is simply to hot and not enough moisture for redwoods to go properly (they will survive but probably won't get over 70ft in these conditions). Sequoias are high elevation and more arid trees and likely won't grow that big in those conditions.
He mention the roots should 30ft after two years of planting. Any arborist knows the generic formula for root spread is dbh x 1.5 ft. 30ft means these trees are slightly over 20" in diameter which for a redwood would easily be over 70 ft height by that point naturally. I'm pretty sure he wasn't moving massive trees around for planting.
He says they will be giants in a few years, this is absolutely a wrong for their growth (a normal healthy redwood can pack on 3-4 ft a year under ideal conditions of non reactionary growth) to say in a few years they will be over 100 ft is just wrong.
He was complaining about being fined for damages from his tree. Full stop red flag right here, any arborist would know this before they even took the ISA exam to be an arborist. You're always responsible for your trees and if they tear up the sidewalk you're liable. Like this is incredibly basic forestry stuff right here like you're responsible for your house plumbing not the water company.
General Sherman got to be that size over at least a thousand years, Steve will probably have a 10-15 ft tall tree in three years assuming it was a cutting that established.
I'm also a forester in Humboldt county and can verify with a mod, I work with redwood trees on a daily basis and everything this guy posted makes no sense.
I think this is a guy who grows pot who got pissed off at the city for his tree and assumed his knowledge of weed translated to knowledge of trees. Also I have never known an arborist to name individual trees just not really something that's done, definetely a pot smoking hippy thing to do though.