I never saw anything like that.
I saw it say Revan knew of the dark power of the place and used that (positioned that battle there) to take advantage of it, but nothing that said Revan was on the surface at the time. Even as powerful as Revan might have been, he/she couldn't have expected to survive the Mass Shadow Generator.
Bao specifically says that Revan was not at the battle.
Illbleed mentions Kreia saying something, but I've never heard her say Revan was at Malachor during the battle in some 13 games.