That was a good documentary, wasn't it? Good topic for a post. Personally, I think that the sinking was accidental for three main reasons:
(i) He was apparently very successful at piracy, and I am skeptical that he had any plans to give it up. In fact, according to The Queen Anne's Revenge: Blackbeard's Mighty Pirate Ship, the QAR sank in June of 1718 and Blackbeard had already returned to piracy within a few months (before being killed by pirate hunters in November of the same year).
(ii) If Blackbeard was a strategic thinker like the narrator claimed, he would have known that betraying his crew would harm his credibility and impair his ability to recruit in the future.
(iii) As they discussed in the documentary, the underwater archaeologists found an anchor on the ground that was positioned as-if the crew had tried to use it to drag the ship off of the sand bar and back out to deeper water.
FYI, here is another interesting video on the underwater recovery effort, although it's more than half a decade old now:
P.S. No upvote necessary. Conserve the beneficiary rewards for others who might still join the discussion.