It is because not everyone sees Israel as committing war crimes. I'm not looking in getting into a debate about it, I don't think this is the appropriate thread and do not want to run afoul of HN guidelines. But to treat your question as if it is serious and sincere (i.e. not a rhetorical question) the answer is because many do not see Israel as committing war crimes but basically everyone agreed China was censoring. I'd also add that censorship can be a particularly sensitive topic the tech community is largely more polarized against than the wider country, whereas weapons of war are viewed by some as valid defensive work. Basically, nerds care about censorship disproportionately. And of course, opinions on both China and Israel would be baked into this too.
Again, not looking to get into the actual substance of these points here, merely answering your question for why large amounts of people see these as different.