RTD elaborated on this in The Writer's Tale, when discussing why so many casting announcements were made at times when it meant giving spoilers away for the show, like Eccleston's departure being announced at such an early point being because the Charter compelled them to tell the truth when asked. If anything these evasive non-answers sound like they realized they were giving away too many spoilers and now stick with "no comment" as a means of preserving the spoilers without technically violating the Charter.
Indeed, the last time I saw an evasive non-answer like this from the BBC was in 2013 when the tabloids began reporting that missing episodes from the classic era had been found to which BBC also responded by saying they can't comment on the matter at this time. And that report turned out to be true, there were indeed missing episodes that had indeed been found around the time the tabloids first reported the matter.
So when BBC declines to comment, that means there's something to the tabloid reports.
