That game was a bad example though pickles
You were in a very special , extremely good position diplomacywise . I as arco was at peace with you so i had no interest in dispelling your forge . The only other good astralnation in the game , Ryleh was very peaceful too .
But normally dispelling is not so easy
. If you can avoid it you always avoid it normally because you never know how many gems your opponent put into it and so unless verylategame or because you are at war with the one with Forge up it is not so likely to get dispelled .