Being a tyrant has little to do with term limits or office duration.
- Ruler who is unrestrained by law or constitution
- A usurper of sovereignty
- Ruler who uses power oppressively or unjustly
Obviously b) is not applicable as per GP. He has also been constrained by the supreme court and others multiple times in this term, which suggests a) is a stretch. c) probably a fair accusation, though I'm not sure I would agree.