I think he needs to strike a balance between exerting his own power in the relationship but holding short of making it into a confrontation that could escalate further. In this way he needs to differentiate because it seems to be they are both very enmeshed.
I don't know that this is necessarily true. I don't think NOP ever came off purposely trying to 'anger' Mrs. NOP, but I don't think he was worried if she, in fact, did get pissed off as he confronted the situation. As a matter of fact, he knew she was in all likelyhood going to be pissed, and there was going to be escalation. Which there was.
It took some stopping and starting and adjusting and retrying on both their parts. This did not happen overnight. More like a two year period (NOPS?). But... he remained consistent... and more importantly, he remained open and began to listen to her wants and needs as well (as MoJo and LFL have suggested HD also do with Mrs. HD).
I don't know that HD should purposely anger Mrs. HD., and I don't think he should fan the flames, on purpose, if she gets there... but I don't think he should back off his simple, calm, repetitive statement simply because he wants to avoid possible escalation. Ewh. Talk about placating.
He has picked his battle, IMO. I think Honeypot is right on with her predictions and advice as well.