*** I Do Not Program / Script Tables *** ... but do like to understand how various actions etc. are achieved
Could you use a switch on either side of the 'horse shoe', along with associated timers - and use the LastSwitchHit command with them to get the desired outcome?
i.e. if the last switch hit was the "Left" side of the 'horse shoe' - it's associated timer would start... then - if the last switch hit then equals the "right" side of the 'horse shoe' and the "left" timer still running then do not 'push the monster' [hopefully this makes sense?].
Also - I mention the 'Side' of the horse shoe because the captive ball will undoubtedly rest of the end of the '"shoe" on the respective side, which could possibly be easier to script/achieve (in my simple mind anyway... LOL).
I'm sure there will be plenty of ways to script what you would like to achieve, and the authors of tables that still visit the forums could suggest more efficient scripting methods.