I don't know if this little story is true. If it is, it might just mean they haven't spoken to each other for a really long time, and then who knows why? So it must have been an embarrassment for both of them. But who knows how they behaved with one another in the last year? Maybe if neither of them called each other in the last year, after all the time they spent together as respectively best friend and husband of the same person, I guess she could have said hi and then just declined the drink. IT THIS IS TRUE. Just turning your back is not that great, but as far as I can remember, when she shared her opinion on the matter in Vanity Fair (if I can remember correctly), she did say she always saw him as an honest person and did NOT say anything bad about him. So I guess, it's just a shame if after so long they have to bump into each other at the Beverly Hills Hotel in front of witnesses and cameras or what ever. If they haven't meant or spoken since their last vacation together, just before the break-up, well, it's just too bad for them, unless they both chose to do so.
He could also have suggested a drink earlier, and/or not in public. Maybe she declined earlier, and made it clear 'whose side she was on'. Maybe he did, or he didn't, and if he did not contact her for a whole year, even to say, hey, it's gonna be hard for us all to pretend nothing happened, or what ever, well if I were her, maybe I'd also turn my back. Only hearing about your ex-friend / friend's ex in the media must be tough IF YOU CARE. Or she could have done the same, tried to call and... Or whatever. What do we know? We don't. I don't know. We don't even know if Jen and Brad speak!! (yes, she said they did, but she had said they didn't for six months.)
So, taken out of the context of Courteney's and Brad's personal relationship, I just think it's hard to judge.