[biot]

The mentions of obesity and diabetes are written as direct causal relationships. To rearrange their quote without changing the meaning:

  "because low-calorie sweeteners do not have an effect on
   appetite, blood glucose levels or weight gain, they are not
   associated with an increased risk of obesity and diabetes"

Essentially, this says "if (no effect) then (no risk caused by effects)". As long as it's true that low-calorie sweeteners themselves don't have an effect on appetite, blood glucose levels, or weight gain then they're free to make the above implication. However, the statement is only a partial truth and has no bearing on the study under discussion.

If they wanted to directly respond to the study, they wouldn't keep quoting old studies which didn't attempt to investigate the results of the new research; they should instead say that they will study it and attempt to replicate the results, then issue a statement once they've understood the full implications. Of course, that wouldn't be a strong defensive statement of their vested interest so they of course can't say that.