The Clarets have not won against their fierce rivals since 'Video Killed The Radio Star' was at number one in the charts back in 1979, yet their long wait for victory appeared to be coming to an end courtesy of substitute Junior Stanislas's glorious 25-yard strike in the 76th minute.
"It's not a great decision from Scott but the way it's gone in is truly incredible," said Dyche.
"It could bounce anywhere and it happens to spin over your goalkeeper."
Williamson had only been on the pitch a matter of minutes and Rovers boss Gary Bowyer had "no qualms" over the dismissal, with Dyche himself suggesting the substitute was left with little choice but to bring down his forward.
Dyche added: "If you're a fan you don't ideally want to see that because you presuppose our lad's going through to score a goal.
"Players have to make decisions and, that late in the game, I would suggest it's a good decision on their part."
All three of the derbies in which Dyche has been Clarets manager have now ended 1-1 and, after David Dunn saved Rovers with a stoppage-time equaliser which looked offside back in March, the hosts were left wondering how many more get-out-of-jail cards are stashed at Ewood Park.
"I think there's a disappointment because they know they've done enough again," said Dyche of his dejected dressing room.
"In all the games against Blackburn since I've been manager I think we've done enough in every game to win it.
"One was taken away from us by a decision, another by a bit of luck here and the first one I think it's fair to say by their goalkeeper. It'll come."