[contravariant]

That just means that the game of life simulation isn't a Turing machine in itself. You don't need to be able to change the size of the Game of Life grid at runtime, it's good enough if you're able to do so by changing the code.

Now I suppose you would run into problems with programs that write arbitrary amounts of data, but then again that's a limitation of nearly all practical 'Turing machines'. You can (probably) make a Makefile simulating a Turing machine with a tape of any size you want, so in a sense it's 'close enough'.