I don’t know this subject so well, but stama generally means that we can assume that it is use for A”Z, while safek means that we have a doubt. The Shach is saying that since it is the regular way of villages to create their statues for A”Z, we have to assume that it was built in this village for A”Z as well. However, it is the normal way for cities to build the statues for beauty. Therefore, we can assume that it was not used for A”Z and we don’t even have a doubt about it. However, if in the village case, there is a reason to doubt if the statue was built for beauty or A”Z, we are machimir and treat it like A”Z. I hope that this is helpful.
