Thaimonk has brought up some important questions. To say Dorje Shugden is a spirit and all lamas who practice Dorje Shugden are going to Three Lower Realms is very dangerous and hypocritical at the same time.
This is not only apply to FPMT, but all the dharma centres and even individuals who claim that those who are practising Dorje Shugden will be going to hell. For Lama Zopa Rinpoche to abandon Dorje Shugden practice passed down by his guru and the founder of FPMT Lama Yeshe, he is actually abandon his guru, throw his samaya, all the other teachings, practices or initiations from his Lama Yeshe to the drain. There's no such rules that student can choose to practice 99 practices passed down by the guru and gives up 1 practice (whether Dorje Shugden or any other practices) by your guru; and you are still consider holding your samaya well and intact.
Furthermore, all the teachings, initiations and practices passed down by Lama Yeshe will be not valid, and there will be no blessings for those who receive it, since you have denounce your guru, your lineage - the very source of all the blessings come from. Since the source has been polluted, then the down stream (all the teachings, initiations or practices being passed down), will be polluted and not pure as well. How come total 100 practices passed down by a demon worshiper, would be the other 99 teachings will be PURE and VALID, but only the one - Dorje Shugden is POLLUTED? Illogical. How can you separate the CLEAN water then the POLLUTED water from the whole stream of water from the ocean of your guru's teachings, and pick the CLEAN ones to pass down, abandon the POLLUTED one?
Not only that, after breaking the samaya, abandoning one's guru, FMPT centres around the world go out to attack centres which practice Dorje Shugden and create troubles for those centres. It's wrong to attack other dharma centres even they're not from the same lineage, and it's even worse when you attack with political motivation in heart - to woo members from these centres, to attract more funds and support from HHDL...
I do believe Lama Zopa Rinpoche is a real practitioner, he must have some reasons he does not want to tell to denounce Dorje Shugden practice passed down by his guru Lama Yeshe. FMPT and Lama Zopa's students should see through this and stop immediately to attack any dharma centre which practice Dorje Shugden; and explain the logic behind abandoning Dorje Shugden practice is abandoning Lama Yeshe, reviving the practice is repairing the samaya with Lama Yeshe the founder, and getting life to the empty and invalid FPMT. It's still not too late to do so. May be Lama Osel will be coming back to FPMT and teaches intensively, and fulfilling his deeds as his previous incarnation did.