Makes sense; he also kills and/or incapactitates some ridiculous number of guards in that story. Truly, K-9 is to be underestimated at your peril... ;D

Yeah, I can see that - he tells her to stay in the TARDIS while he takes care of something, but naturally she thinks she knows better... Or as you say, Romana and Susan alone without the Doctor knowing about it - that might make for an interesting conversation...