Arturo, I think you are right in saying that the situation of the Jews under Mussolinis antisemitic laws, as ratified by Vittorio Emanuele III, was different from the situation of the Jews in Germany back then. First, there were only about 50,000 Jews in Italy. Most of them even supported Mussolini for a very long time. As long as both Mussolini and Vittorio Emanuele were in power, there were no concentration camps, no death sentences - that all only started when Italy surrendered to the Allies and Germany invaded the north of Italy - it were the Germans who deported and murdered the Jews of Italy.
Mussolini "just" arrested or exiled Jews and antifascists to Southern Italy - maybe some of you know the famous book "Christ stopped at Eboli" - it's the work of Carlo Levi, an exiled Jew from Torino, and it's autobiographical.
I don't write that to defend the (then without any doubt existing) Italian fascism, or any of the actions of Vittorio Emanuele, I just want to point out that the European History in the years before and during World War Two was VERY complex and I think that Vittorio Emanuele had reasons to believe that to give this signature was the better solution than to deny it. Vittorio Emanuele was at that time the only one, in his role as King, who had a certain contitutional power to hold Mussolini back. Not signing that bill would have meant giving that up in the last consequence (as Mussolini might have abandoned the Monarchy by coup), which VE might have considered even worse, fearing that all hell would brake loose then, as Mussolini was clearly dangerous and eager to please Hitler.
Uhm, that's pretty f*^king horrible too.
They don't deserve credit for not sending anybody directly to a camp. What they did is absolutely completely horrible on its own. I've no doubt the situation was complex, but arresting and exiling people because of their ethnic and religious background is disgusting and unacceptable, even if a government to the north was doing far worse.
I don't think the guy's rotten corpse deserves to take up space in an honored grave, but that's just my opinion.