In regards to how bitcoin can solve inflation in a third-world country, I think that bitcoin wouldn't make any difference or significant change to that problem because most third-world country that's experiencing high and uncontrollable inflation are countries that have incompetent leaders and officials, if you root out corruption and place competent and smart people on the important seats in the government, you can easily see changes but given that not a lot of people has done this in these countries, I am not entirely that purging the corruption might be the solution.
I can't say I agree with the impact of bitcoin being so small or insignificant when it comes to helping alleviate inflation in a country let alone a third-world but I definitely agree with you 100% that corruption in the government is a pretty big help if a country wants to combat inflation, I haven't done a research yet but there's probably studies to prove that there's a relativity when it comes to a country's prosperity and it's government's competency and incorruptibility.