You have to tick all three boxes for it to be terrorism.
Box (a) is definitely ticked, no question about that.
Box (b), he wasn't trying to intimidate the public. Was he trying to influence the government? Maybe, it was retribution for wrongs he considered the police to have carried out against him. You could argue that he was trying to influence the police not to commit those wrongs.
Box (c), was it for a political cause - not really, religious - no, racial - no, ideological - not really. It was a personal vendetta against the police.
The (a) offences listed in section 2 are criminal offences elsewhere in criminal law. They only become terrorism if they are used to advance the aims in (b) and (c).