Yes, but it wouldn't have mattered if the goldfish had been kept in the Teddy Tank or a regular 30gal, if your cousin poured soda in it.
If I'm not mistaken, iluvfish's opinion has nothing really to do with the size of the bowl but that the concept of the Teddy Tank is a good concept that could have positive effects.
That said, I have to say I would object to the Teddy Tank whether it's a bear wrapped around a 1 gallon bowl or a bear wrapped around a 20gal tank. I just don't like it. I feel that it takes away from the fish, who should be the centerpiece of any fishkeeping setup.
I don't like this thing due to personal experience reasons only. My aunt bought this for my 5 year old cousin and bought him a cute little betta fish. Everything was fine at first and he absolutely loved feeding the teddy bear and seeing the betta eat it. But when my cousin learned that he would have to clean the tank he began completely ignoring it. His parents had to feed the fish, and they told him to clean the tank again...he was in a bad mood and raged at his parents, then ripped the bowl out and flushed his betta because, and I quote him, 'the teddy bear never did anything and I didn't want to clean it because it wasn't dirty.'
I realize that not every kid is like this, and some may be interested in feeding and cleaning up after the fish...however, if one kid is capable of completely ignoring and later killing his pet because of lack of interest in his toy than I'm sure that many more kids can do the same.
This is just.... disturbing. I don't think kids 7+ would harm their fish because of this, but younger kids might, and they are the ones that would want it more. Plus, it takes away from the fish. If you want a fish, get a fish. If you want a teddy bear, get a teddy bear. Not both wrapped into one. I can just picture this conversation:
Timmy: Mommy can I sleep with Mr Fishy and Mr Bear tonight?
Mom: No Billy, you cannot.
The multiple responses of Timmy:
Sleeps with it anyways.
Gets mad and throws it on the ground.
Takes the bear off the tank, and the tank spills.