Dark vision is amazing and not taking a penalty for multi-classing into barbarian is the icing on the cake. But the stat line "+2 str -2 int -2 cha" is a bit of a curve ball though and could hold you back as a druid.
According to the Druid's handbook there's a workaround.
desert half-orc environmental racial variant
combined with the Racial substitution levels
could be a badass
The racial substitution levels for Half-Orc Druids get d10 HP and also gets some fucking sweet animal companion stuff, they even have an option for barbarian substitution levels if you want. Of course, you don't have to use these substitution levels if you don't want to but it's highly recommended you do as the abilities changed here work much more well with a Half-Orcs stats.
Originally Posted by Desert Half-Orc environmental racial variant
The sad thing is, you'd lose your darkvision. But the stat line is less crushing on this Half-Orc.
I can see why the guide suggests it, but if the normal race is more your cup of tea I can still see it working.
My final advice for making the character "optimal" is that the strongest druids often don't multi-class at all, as their level scaling is just so fantastic. But barbarian would be the pick I feel like, as the barbarian class is one of if not the best
class to split into.
I recommend just taking a 1 or 2 level dip in barbarian at most. As what you get from your druid class could make you even deadlier.