Malphite getting hit and still get recalled

If you don't take damage your recall won't get cancelled.

If you have a shield, like say malphite passive, and the damage you take doesn't break it, and thus doesn't actually damage your hp, it doesn't stop recalls.

There's also a fringe case where the last fraction of a second of a recall cannot be cancelled. That is because the back signal has already been sent to the client from the server, and the damage signal won't arrive on the server before the back is completed. In those cases, you'll often see players complain that they took damage in fountain.

Obviously, that doesn't apply to this case (on champions without shields, that would have stopped the recall), but the point remains.