The proof itself is quite self-evident: given a perfectly randomly block generator, and infinite play time, eventually you're going to produce a very long sequence of left- (or right-) facing S-blocks. Since those are impossible to eliminate (there's always one block left open on a row) eventually you lose.
https://www.researchgate.net/publication/2347389_How_to_Lose...
The proof itself is quite self-evident: given a perfectly randomly block generator, and infinite play time, eventually you're going to produce a very long sequence of left- (or right-) facing S-blocks. Since those are impossible to eliminate (there's always one block left open on a row) eventually you lose.