if a and (b1 or b2 or b3) and c
terrorist = true
end if a and (b1 or b2 or b3) and c
terrorist = true
endSo an attack designed to destroy an unoccupied building would not be terrorism under the structure you describe above.
The definition does not state that all of the clauses must be satisfied for something to qualify as terrorism, and as I showed above, satisfying a single clause is trivial (and clearly not terrorism).
Logic would dictate that the meaning of that is "if A and (B[1] or B[2] or B[3]) and C", but it's not explicitly there.