I was actually a tiny bit disappointed - I was hoping for a closer coupling of tetris-logic to life-logic :-) Per https://conwaylife.com/wiki/Universal_computer the first turing-machine-in-Life goes back to 2000, and "building a CPU to run code" is at this point the "obvious" way to do it. See https://nicholas.carlini.com/writing/2020/intro-to-circuits-... for a tutorial with a (circular) "final goal of designing an Intel 4004 and using it to simulate the game of life."
Right, they made the odd choice to use Life to simulate a different cellular automaton and then built logic gates in that automaton. But you can in fact build logic gates directly with gliders in the Game of Life itself. The extra level of abstraction multiplies the area of the final result by about 20000.