Hungary doesn't have a refugees problem. that is, they don't want to stay in hungary and they have not magically arrived in hungary so hungary is not the first EU state they landed in thus not forced by any international law to accept them. those imaginary 50K would have gone by themselves to Germany since merkel invited them in, instead, with the quota plan, they will now be "encouraged" to stay in hungary for their impending relocation which could take many months to accomplish, and on top of that, some of which will get refugee status in hungary or other states where they don't want to be in. good luck moving these people. since we are talking about the equivalent of the mere last 20 days of migration into the EU, hungary knows that this precedent will have far bigger impacts than merely accepting ~1500 refugees. for example: It hasn't been decided who these 120K are, so more migrants will swarm to hungary avoiding registration in other countries on the way in the hopes of hitting the lucky 120K. it will require their registration in hungary which means that if they are not in the lucky 120k, they will be "forced" to stay in hungary by the international law.
So in Orban's mind, 120K is a meaningless number which is only a drop in the ocean and any quota is irrelevant if Europe doesn't set a cap to overall refugees and means to enforce that cap so to prevent refugees from entering Europe in the first place. his objection was a symbolic one indicating that if they want his vote, they should regard his plans. another thing that pissed Orban was the subject of sovereignty of the EU states. He simply can't accept that Germany is deciding for him how many immigrants/refugees he should accept.