I agree with you, but I admit I felt somewhat uncomfortable being the arbiter of tags, particularly given the attacks Nettaigyo has been taking as of late. Under-promise but over-deliver seemed safer to me than the reverse... but I suppose we can let consensus decide here...
It for sure has more the CGDQT playful gay feel to it than anything too serious but it is gay as hell... As Eggnsrice mentioned it is gayer than a fair few series marked as yuri as well, "Futari Escape" being a good example (which I love, and thank you knight heron for it)
I think the yuri tag would be fine on it, but I am not too fussed about tags really and usually read a chapter before even looking at them... So maybe not the best person.