I don't feel like she was coming off as a tyrant in "Latent Image" at all. She'd already been through all the ethical implications of rewriting the Doctor's program back when she did it the first time, which is why she wasn't open to discussion the second time initially, why retread old ground? But she did actually come around and change her mind.
As for the rest of the time...well she IS a military captain and I wouldn't really say she consistently cruel to the crew so I wouldn't say she was a tyrant no.