This is anecdotal, but in recent years, I believe the rate of Iranian tourists and expats has increased. This is more or less evident with more of these Iranian restaurants spawning throughout Pattaya although compared with other ethnic groups, they might not shine in numbers.
You are right regarding Iranian being involved in commerce and business (I even heard the "Arab," who is giving the Soi Cowboy of Bangkok a face lift, is in fact an Iranian). They are shrewd in some regards when it comes to digging money as an outsider, no matter where they find their foot hold in the world. I have also read about the presence of Iranian drug traffickers and [petty] criminal elements in major cities. What a shame.
A recent story I read earlier this year was about a defected high level Iranian intelligence officer, who was running a jewelry store in Bangkok, and evidently began a few years of cooperation with two other anti-Iranian regime individuals to push for a revolutionary movement from the outside of the country. The funny thing is that the aforementioned person of interest immediately abandoned this newly formed group and flew back to the bosoms of the Mullahs and made a series of propaganda appearances to depict the protests of post 2009 presidential election as a product of his former colleagues' foreign agenda to topple the regime.
P.S. I thought the "alleged" bomber was acquitted a few years later, wasn't he? Whoever the driver was, he had apparently murdered the truck service employee at the back of the truck he was driving, so one can assume it was a robbery of some sort and since no real perpetrator was identified, the proximity of truck carrying certain explosive material to Israeli embassy might have been coincidental.