As a general rule Disney does not automatically deduct TS credits if you miss or cancel an ADR. (Not guaranteeing that it's never happened, but if it did, it should be something you could get corrected via your hotel front desk or guest services.) Now, there are some TS places (Fantasmic Dining Pkg for example) that require a credit card to book your ADR even if you plan to pay for that meal with
DDP credits, and if you miss or fail to cancel at least 48 hrs. in advance your credit card will be charged (but no DDP credits should be deducted). For all other TS places, missing or canceling your ADR results in no penalty (in fact, canceling your ADR as soon as you know you aren't going to make it is the courteous thing to do).
However, because TS dining is so popular now, if you miss or cancel an ADR, especially at the last minute, you run the risk of not being able to find a replacement place/time that works for you. I would guess that this is what was meant in the other thread - depending on your flexibility (or more accurately, lack thereof), you might
effectively lose the
ability to use the TS credit you had intended to use at the ADR you canceled.