We all love and revere Reagan, but the truth is the truth.
Signing the 1986 amnesty bill was an act, that in retrospect, borders on treason. It opened the floodgates for the third world to invade our country, forever altering the character of our nation. It also saved the Democrat party from certain death, by replenishing their falling voter rolls.
Had Reagan stood firm and simply enforced our immigration laws, we may never have suffered the subsequent rise of the radical left, and all the attendant destruction that has done to America.
I think you may not have a full take on this issue. Treason is far from what happened.
Reagan had a lot on his plate. He had an agenda that was at times overwhelming, and he had to trade things off of his priority list.
He never had a Republican House, there were 269 rats in 1982, and 253 in 1984. The Republican senate was pretty RINOish as well.
He had rejuvenated the American economy, but was in the midst of killing the biggest evil in the world at that time, the Soviet Union.
He traded for the funding of the military, and the killing of Soviet communism for something that looked small. Yep, he thought the dems would help stop the invasion, back then they were plausibly in the fight to control the borders.
In 20/20 hindsight, we know that the democrats were just as evil as the Soviets, but at its worst, he trusted the dems would help control the borders. He got it wrong, but only because the dems had left the love of America for the vision of Howard Zinn. That was not yet clear to anyone. It was not treasonous on the part of Reagan, it was on the part of the dems.
Quite frankly, it was the Bush family who capitulated, not him. He thought he had a deal, the Bush family looked the other way. Heck, they even encouraged it. HW Bush was the one who gave away the store, not Reagan.