There are plenty of arguments in favor of cutting aid to Israel. As a strong supporter of Israel, I even think there's a case to be made that cutting aid would actually be a good thing for Israel in the long run, because then they'd have a freer hand to do what they need to do militarily, and could be in a better position to resist pressure for constant concessions to their adversaries.
But perhaps I should have offered a bit more context in my post. Ron Paul's foreign policy views are well known. They are shared by many libertarians and a subset of conservatives, but -- broadly speaking -- are not representative of the views of most conservatives. When it comes to Israel, I know that Ron Paul's defenders would argue that he isn't pro or anti, but merely neutral, in keeping with his non-interventionist views. However, the way he goes out of his way to condemn Israel on a regular basis undermines that argument. For instance, when Israel invaded Gaza to go after the terrorist group Hamas, Ron Paul released a video. Sure, he said we shouldn't take a side, but his arguments were those of Israel's adversaries. He referred to Palestinians in Gaza as living in a "concentration camp," a term which is of particular historical significance to Jews, and he dismissed the threat from Hamas, claiming they only had "a few small missiles."
So when Rand decided to run for Senate, we all knew where he stood on fiscal policy, but the big question was whether or not he agreed with his father's views on foreign policy. Luckily for Rand, his Senate race was dominated by domestic issues and Aqua Buddha, allowing him to thread the needle on foreign policy. Many supporters of his father assumed he was with them, while those who disagreed with the elder Paul on foreign policy were generally willing to give him the benefit of the doubt that he was different from his father, although there were skeptics.
When Rand revealed his budget plan, he came under fire for ending aid to Israel, but not from me -- because it was part of a $500 billion budget-cutting package that also eliminated all other foreign aid. Yet when he specifically refers to aid to Israel as "welfare," it comes off as resentful toward the country, and helps add to the perception that his foreign policy views really are in line with his father's -- which could be a good or bad thing, depending on your perspective. If his aim is to play to the Lew Rockwell crowd, such terminology is perfectly appropriate. But if he wants to convince small government conservatives -- who broadly support Israel -- that we cannot afford foreign aid, then I just don't think it's very helpful to his cause.