I cannot think of any Church or major theologian who teaches that simply not knowing about Jesus means that someone experiences port mortem salvation or escapes Hell (unless they're universalists, in which case the point is moot anyways). You're confusing the idea that someone who hasn't heard about Christ can be saved with the idea that someone who hasn't heard about Christ will be saved.

Think of an analogy to cancer treatment. There are people with cancer who are healed without treatment. You can survive cancer without treatment. Likewise, there are plenty of people who undergo treatment and end up dying anyways. These statements don't at all imply that doctors shouldn't be giving cancer patients treatment just because it's possible they could survive without it. The same logic easily applies to Christian missionaries looking to 'save souls' in unevangelized areas.