Yes it's not applicable for Blackberry handsets. I thinks it's beacuse of the capability of blackberry devices to compress the data that it downloads and also blackberry has separate promos with Globe like BBMAX, etc.
They are right. Blackberry phones with OS 7 below are not capable to access Free FB because those BB phone still uses BIS (Blackberry Internet Service). Thus, there are other BB users who happen to use free fb at their handsets so you still wanna give it another try. just search this link on your browser: m.facebook.com/free and log in there.