He can't come out and say "fuck off we're full, the Marines are coming to throw your asses out this weekend." The TechBros would turn on him and the Boomers would lose their shit becuase the line wouldn't go up and logistically no one would be able to obey even if they WANTED to and whoops, turns out if you order something done as a leader and they defy you you have a huge problem.
We need to get to 0 H-1Bs. How do we get there? By slowly tightening the noose around the techbros, cutting them off from their serfs. Make it a pain in the ass to get H-1Bs, make it so they're not the I-Win button solution to payroll, et cetra. Each step makes it more appealing to just use Americans instead.
Trump is like a reflecting pool for retards. You can see whatever you want to see in him. There's always a whisper that he's playing 8th dimensional chess, but in reality, he's just great at fleecing people that he convinces they are on his side.
Look at it this way, if Trump really, really wanted to get rid of H-1B he could easily rid every single Trump company from every single one and put forth a great press release talking about how he employs 100% Americans and blah blah blah. He won't do that of course, because he (and his corporate overlords) love love love love the fat profit margins they can get for paying H-1B workers far, far less than an American. The benefits don't just end at lower pay -- these H-1B workers are basically indentured servants. For many of them, their very presence in the country is coupled to whatever tech job they currently hold. They are the last people on earth to make waves at a company. Cheap workers that don't cause trouble? Sounds like a dream for a corporation that doesn't particularly care how many Americans they employ.
Trump stands to benefit far, far, far more if H-1B program continues into the future because it saves him money every single day it's active. Of course he's not going to eliminate it.
This is no better than him meeting with all the coal miners in WV and telling them coal is the fuel of the future and blah blah, and then a few months later slashing all their safety regulations, screenings for black lung, labor regulations, etc. Those coal miners don't feel so good anymore. Although, I bet a lot of them would still vote Trump next time. Hell, there are people who have been deported themselves or have had family members deported that are still Trump supporters. It's sad they are willing to fall on a sword for Trump, because he sure as shit doesn't fall on any swords himself.
The American people are awfully easy to fool. Just go in front of them and promise them the world. They don't check up on you later, or even ask for consistency. Trump has learned very well that he can say and promise anything to everyone (even contradictory things) because no one REALLY holds him accountable. They just do what you did and say he's some political mastermind.
My only regret is that I'm not some multi-millionaire, because that's who Trump really cares about in the US. The rest of us are just rubes to be exploited. Keep waiting for Trump to fire all the H-1B workers and staff exclusively Americans at his companies. You'll be waiting a fucking long time, because he's never going to do that, as long as it saves him money and trouble.