If you ban chimp testing, you are forbidding people from making moral decisions. If you really cared about the suffering of sentient beings, you would also care about the suffering of humans; and you would realize that there is a tradeoff between the suffering from those experimented on, and those who benefit, that is different for every experiment.

Banning testing on our closest living relatives is a powerful moral decision in itself. By resisting a ban, you are forbidding people from making moral decisions. You may as well apply your argument to any bans whatsoever. When something is generally wrong, we ban it. Prohibiting painful and invasive testing on chimpanzees is quite consistent with attempting to minimize suffering across species. Not only are there alternatives, but experimenting on chimpanzees is logically inconsistent with a number of ethical theories. Since we have status quo bias and tend to rationalize self-interest it is right to be skeptical of chimpanzee testing.