I understood his showing his frustration at home slightly more, but I think that two professionals like Lois and Clark would behave accordingly no matter their personal feelings of the moment while at work.
Well, considering that there was a slew of unprofessional behavior (i.e. parties and kissing on the job, etc.) throughout the series, I didn't really see anything different about the unprofessionalism in this episode (although, there was a greater degree of it).
