I think that's also possibly easy to accidentally trigger on touchscreen for those that are clumsy like myself :D. I have 0 experience in any dev, so not sure if it would be really annoying for you; but maybe even something like a "Clear Tile?" confirmation pop-up if the tile is occupied?
Hm, that would be 100% safe but probably inconvenient as well. Perhaps I make a setting in the menu.
I already published my modified version with swap triggered button, it's called The Sailor & his Garden. You can check it out (better to check tomorrow cuz i made online leaderboards and today it doesn't work)