Not "rules" but "guidelines". Or quite literally, "principles".
"... stock soars"
The thing is that GAAP vs Non-GAAP is pretty irrelevant unless they regularly change how they do it. If a company reports non-GAAP earnings every quarter with the same methodology, it's effectively the same as reporting GAAP. People on wall street aren't dumb. There is a reason the reaction was positive.
Food for thought, here are GAAP vs non-GAAP reportings for the S&P 500 companies: http://www.auditanalytics.com/blog/wp-content/uploads/2015/1...
For the non-finance people, this is like using snake case in a camel case language or vice versa. Sure, it's an annoyance the first time you look at the project. As long as it's consistent between files, it's not really worth withdrawing from your "things I can bitch about at the dinner table" account.