Although the airfield (not airport) at the St Catharines end of the Niagara Stone Road can handle small a/c of the flying school and general aviation type, it has none of the support services that would turn it into an airport. With BUF so near, folks will just drive another 20 minutes and save the cross-border fees charged by the feds so there is no incentive to upgrade it.
YHM is served by WS, but for the rest is largely used for freight (and sports teams). It has proven not to be profitable for other carriers (especially once YTZ became busy) which is why AC withdrew from there. The only time I fly out of there is on vintage planes from the Canadian Warplane Heritage Museum, of which we have been members for many years.