Yes passion flower is a rather weak MAOI. It only has about 1mg harmala alkaloids/gram of the herb. S. rue seeds have about 30mg of harmala alkaloids/gram. However, I don't think that the interaction between the SD and harmala alkaloids is a MAOI one, anyway. I'm thinking that it is just a regular synergy. Harmala alkaloids are said to synergize the effects of Cannabis/THC too, and that is not an MAOI interaction either.
As far as smoking harmala alkaloids, it can be done. A Syrian rue seed extract laced onto some SD leaf could be make for an interesting dream.
