The fact that Chronicles 1 - even though it was retconned to be written from an in-universe POV because Shadowlands directly contradicted a lot of it - corroborates the ask CDev answer only makes it seem more likely.
It’s also not totally incompatible with the legendary version of them being “created” by Vek’lor. He might have taken existing Titan forges and twisted them to create these corrupted Tol’vir forms. In that case he would be their creator, but they would still be corrupted Tol’vir.
Of course, it’s a retcon to the description we got in WoW Classic since the Tol’vir literally didn’t exist back then but that’s just where we’re at now. Can’t really get around the fact that they resemble them to a tee.
All you’re basing your theory on is the fact that Titans erased history of the Black Empire and overstated their own achievements. Nothing about that inherently has anything to do with who created what race.
In any case, even if you were somehow right, it still wouldn’t address the aesthetical overlap between Maldraxxus and the Scourge. The Scourge aesthetic is a random agglomeration of different cultures that were absorbed by the Scourge. You have Orc influences, Legion influences, Nerubian influences (which even if you take away the aforementioned Titan influences had no relationship with the Shadowlands), human influences etc. which is all in all a very specific cocktail. The fact that Maldraxxus contains all of those same design elements with none of the specific history that gave rise to them simply makes no sense.
I mean, even simple things like the Liches of Maldraxxus using frost magic makes no sense, since WC3 stated that the frost magic of Liches is a gift granted to them by Ner’zhul who tapped into “furious elements of the cold north”.
Let’s just be real here and call it how it is. They copied it without giving it a second thought, which would be fine if they had made Maldraxxus a Scourge invasion outpost within the Shadowlands, but instead they declared that it’s basically the other way around.