I would contend, but not necessarily in this case, that a third party has as much 'right' to be offended and to complain.
For instance if the 'photocopier clerk' and the 'chief cook and bottle washer' had something going and it was patently obvious, all luvvy dovvey like, then this might annoy my maiden aunt.
Said Aunt would feel harassed by this untoward and unbecoming signs of affection in the work place. She would be quite in order to complain.
FV, see PM.