How was he supposed to know it was going to take him a long time to do it in YAML? A lot of people (inlcluding me) talk up YAML config-file solutions as being relatively simple.

Most programming tasks have a large indeterminancy about how long they'll take -- even the simple ones (like this) sometimes run into some odd hang-up (that leave you feeling like an idiot for spending a day on something that was supposed to take five minutes).