blaming the FSF (Score 1)

I think it's funny they blame the FSF for claiming the two liceneses are incompatible when it was Mozilla who first stated this and intentionally made an incompatable license. I guess the FSF makes an easy scape goat these days.

Old Mozilla

Under our reading of the GPL, it will not be possible to incorporate code covered by the GPL into the Communicator source code base. It is also not possible to use GPLed code and NPLed code together in a Larger Work. This is different for LGPL code. It is possible to create a larger work using LGPLed code that can then be used in conjunction with NPLed code through an API.

New Mozilla

After the NPL and MPL were created, the Free Software Foundation stated that the NPL and MPL were "incompatible" with the GPL. "Incompatibility" in this context means that (in the opinion of the FSF) developers who combined code licensed under the NPL (or MPL) with code licensed under the GPL and distributed the resulting work could not do such distribution without violating the terms of the GPL. Given that the LGPL contains similar language to the GPL, if the MPL were in fact incompatible in this way with the GPL, it would arguably be incompatible with the LGPL as well.