Do you really think a classroom in Yale is in the same category? (I don't)
If the bomb did come from a terrorist bomber, the bomber is likely to be a student or ex-student--and perhaps the specific target was more a matter of "convenience" to the bomber.
Exactly. They are symbols of American power and might. They do not represent either the Left or Right, nor are they supposed to. Terrorists do not differentiate between political persuasions among their targets.