Klumpen0815: Oh dear, it looks like a parody though...
Well, at least they are making clear, that the bible indeed is clearly against gays but they should quote Lev 20:13 and not Lev 20:23 in their title, which many people do not know indeed and should make them reconsider to which belief system they want to belong to.
What exactly do they have against him?
Is it because he was jewish, because he had gay friends or just because they like hatin'?
Mr. Nimoy was a celebrity. Threatening to picket his funeral generates public attention. That is probably the primary reason.
Other reasons? His religious background, his role as Spock (with the "devilish" ears and all) and possibly his social activism. Nimoy was strictly against the discrimination of LGBT people, and that alone would make him a prime target for Westboro.