Considering that it only took Harper one slip to accidentally change the settings to an entire ship and turn it hostile, and to my knowledge it hasn't happened with other manual users, I would suspect that it is the dataport. But I will ask for more investigation because that is something that needs to be answered. [People may be so focused on preventing Tosh from doing it again that he should eliminate that chance that someone else could do it.

And he gives another moment of thought.]

Rinzler was incredibly fond of you and what you did for him. It is unfortunate that you lost whatever it was that motivated you then.