How long did what take? Learning the essentials of OpenBSD, budget 4-6hours. Switching over servers from Ubuntu, an hour for the first one then 10mins each after that. You can copy config with your favourite tools; most have ports for OpenBSD already.
If you want to learn more in-depth, read: Michael W. Lucas
Absolute OpenBSD, 2nd Edition: Unix for the Practical Paranoid. Highly recommend it as teaches many fundamentals most software engineers skip.
It's really hard to comprehend how entitled "reward which would be the cost of lunch in Sweden can be massive for those low socio-economic-located people" is.
A lunch in central Stockholm is well within 200 kronor. I can't imagine a country where an person with a computer and skills necessary to claim a bounty in cURL would consider that amount massive.
Is he entitled for considering the difficultied from developing countries?
Maybe he's exaggerating a bit with the comparison, but if we consider the ceiling of 10k, that's more than a year of minimum wage in Portugal, or a handful of years in certain developing counties. Certainly significant!