If I jump onto the disappearing block and constantly jump off of it, the block will not disappear. I can also walk onto it briefly, then walk off and if I'm fast enough it will not disappear. I also tried making a line of them and just ran across all of them, without anything happening. Did not test on SA-1 (since it wasn't made to be compatible).
Lastly, this block exists that's already SA-1 compatible and functions well enough already, so this block isn't really necessary.