Worf knows one cannot see how a Breen looks like by removing the helmet of his suit
There's no indication that he does. But that's not the problem with his dialogue at all - the problem is that he thinks witnesses die before singing, which demonstrates he is wholly ignorant of "Indiscretion". And that trumps all idle speculation on what else he might know - we absolutely must
assume that information on the Breen does not travel freely between our DS9 heroes, for whatever odd, silly or dramatically interesting reason.
In other words, no contradictions.
I don't fault the novels from attempting the Space: Above and Beyond
solution. They have thousands of words to spare to make it sound halfway plausible, just like they can afford to spend entire chapters to make "Trip Is Alive!" a mitigated disaster rather than worse. The onscreen dialogue just happens to be more compact, and rather clearly written without continuity in mind, which puts extra pressure on the novels to justify the solution. And it seems the solution in no way helps with Worf's demonstrated ignorance of Kira's achievements in this field.