I see. Well, we could change my statement to: Well, if A is the player, and B is the grass, and you want A to stop when it comes in contact with B, is there any reason you can't use "A Stops"?
But I just tested that out, and it seems the "A Stops" doesn't work very well as a Stopping a Sprite method. I would suggest almost that it be fixed in another release of SGDK but it would remove backwards compatibility if anybody were using it to do what it does now (which is basically imobilize the sprite being stopped). Especially if you land on top of a sprite, rather than stopping, you slowly sink into it. If you walk into the sprite, you go a few pixels in, then are imobilized and can't get out. Hmm....in that case, I would go with BlueMonk's suggestion.