That was the first thing that sprang to my mind too.
OP, I'm unclear as to why you didn't just tell the drink thief straight out that you didn't 'tattle' on her? The 'interesting assumption' line could (and likely did) make it seem as though you did in fact tell on her to the manager. Of course, she may well have disbelieved you even if you'd told her straight out, but I feel the 'interesting assumption' line just aggravated the situation, to be honest.
I did nothing to warrant having to JADE myself to a woman who was clearly ignoring the stipulations of eating in the restaurant in the first place and lying to the cashier by saying she just wanted water. She
made the assumption I had said something. If she'd been close enough, she would have heard that he was asking how we were doing and was concerned that we hadn't been in for a while. The manager is someone DH knows from his very early days (nearly 25 or so years ago) when he and the manager started out at the same local grocery chain, but both went their separate ways when the store closed and the chain closed down. The manager recognized DH when we started going to the salad buffet a couple of years back, and he uses the time when he visits to the table to see how things are going with us. So yes, he was going to spend a little more time than he might with others because he knows us. But he doesn't linger more than maybe five minutes and he's off again.
If anything, she was aggravated by the fact that she was told that sodas were not free, and that she could either pay the minimal price (I believe it's just shy of $2) or leave. Since she didn't want to pay, she was asked to leave. The fact that she got upset at me could have easily have been anyone else who saw her do what she did. Even if I had said I didn't tattle on her, she was upset to the point that she would probably have made a bigger scene if she hadn't been escorted out.
Someone mentioned the colored glasses. This location is part of a national chain, so the manager really doesn't have a lot of say about certain things, other than what's offered at his location. The drinks offered are Coke products, and they have everything but clear sodas. So I think the colored glasses work well. Sure the cost of the meal could be raised to include the drink, but it's already close to $11 per person just with the unlimited meals alone. I'd pay more if it did include the drink because the food is good (plus they have these awesome lava cakes and cobblers for dessert and even hand out cookies to the diners).