Nice to get an opportunity to appreciate Michuru from a sexual standpoint, since in her scenes Airi is normally the ecchi focal point. But Michiru's cute too and has a very nice body.
Are we being punished now we finally got a sex scene out of this?
I'd remind everyone that the sex scene came from the one couple who had, on several occasions, furiously made out with each other. Nobody else has been even close to their level of unambiguous sexual interaction (unless you want to count the sadist/masochist pair, which is ... a bit different). So perhaps "spoiled" is a better term than "punished", but I haven't really been expecting anything more.
My prediction for the next "breakthrough" is that Ayano/Miyoshi will get accidentally drunk on something they didn't know was spiked and have a drunken makeout session. And then pretend they don't remember.