That is one theory, and I am sure there are others. You can't find the true nature of the crime without more investigation.
I do love the irony of the molotov cocktail being not just in any bottle, but a BEER bottle. lol. Gov't says marijuana causes violence then somebody tries to arson a building with a beer bottle. Just lovely. To cite Bill Hicks; this is clearly like ya its ok to drink your drug that's fine. Its those other drugs. The untaxed drugs. ofcourse I'm sure there is a levy placed on MMJ but still the gov't fear mongering of it over the years has certainly had an effect.