It looks like there is no problem finding building materials in Gaza, when the desire is there. And what greater purpose can be served in Gaza than building a brand new mosque in the place that hundreds of Jews lived a few years ago?
I haven't seen any new housing complexes built in the destroyed Jewish communities of Gaza. Mostly they have been used for terrorist training, some agriculture, and now this.
This new mosque was not built because of a pressing humanitarian need. It was built to insult Jews.