chawley650, just curious: what rules of consistent use of tense are violated? To me panel 7 looks good. And the last I recall, Dilbert used to be a comic, not a subject for grammar study.
Rules of grammar don't apply to dialogue. Very few of us walk around speaking the Queen's English. In fact, applying strict rules of grammar to spoken dialogue is one of the best way to make it sound stilted. One of the reasons I like "Dilbert" is that his dialogue sounds so realistic.