In a slight defence of the OP, I believe that it is relatively common practice and I have also invited friends for free drinks and food in hotel lounges when I've been travelling alone without registering them to the room on the basis - from my point of view - that the room charge is the same for one or two occupants and it's a way to catch up with acquaintances in their town for free or at least kick off the evening on the cheap. Certainly I've done this in Singapore, Bangkok, and KL without any lounge dragon turning a hair. I have no idea whether the hotels themselves clock this or care. I suppose I'd file this into the same category as those people who somehow manage to get their elite benefits like lounge access extended to guests in a second room under their Bonvoy number. In other words, YMMV.

On the other hand, I do agree that there's no need for embarrassment and if I was relying on this for a business meeting then I'd quietly ask them to put any charges on my room and encourage my business colleague to get royally slaughtered on the free flow booze as revenge for the hotel being pedantic by strictly following the T&Cs.