Chances are that if you pick a date at random, there will be some heinous crime that the Iranian regime has committed on that day. As to myrtus. Even if we assume that whoever did this knew that myrtus=hadas, very few Israelis who aren't biblical scholars would associate the name Hadas with queen Esther.
I would say that if this is the best we have, then it's pretty certain it's not the Israelis who did this.
Our defense budget is 7% of our GDP, which is the 5th highest rate in the world (according to wiki). I would hardly call that free. Also, there is a shortage of tech talent here and the salaries are quite high. So there are also hidden costs with the military getting people to work for "free".
I would say that if this is the best we have, then it's pretty certain it's not the Israelis who did this.