I believe that Keaton is an expressionist director. However, he can also use realism. According to Bezin, for a film to be realist, the director has to be invisible which is true for Keaton with his use of invisible editing as Keaton only ever uses very minimal editing and only edits when he needs to. To make his editing invisible, Keaton only cuts on an action which is shown in 'One Week' in the spinning house sequence where the only time Keaton cuts is when he jumps into the house. This sequence also matches Bezin's definition of realism as the house is always in the dead center of the screen with no change of camera angle, even when it's spinning around everything stayed in frame with the only visible cut being when Keaton jumped inside the house. Although, there is some expressionism in this sequence as special effects are used to create a storm and the house spinning around is used to create audience pleasure. Another reason why Keaton is more of an expressive filmmaker is because he uses Vaudeville act routines in his films such as the use of the ladder and In 'The High Sign', the use of the banana skin is used for audience pleasure which dates back to the 1890s vaudeville acts when slipping on a banana skin was used for comedic gags. However, in this nobody slips on he skin. This scene shows that the position of women in Keaton's films is progressive as she does not get pushed to the side as Keaton builds their house but instead, has a prominent role in the film alongside Keaton's character. The only time editing is visible in Keaton's films is in the dog chase scene in 'The Scarecrow' where Keaton falls backwards off the building and the camera cuts to him on the ground. This use of visible editing is quite jarring for the audience as we are not accustomed to seeing Keaton cut like that. Other expressionist films at the time which had a narrative was Melies 'A trip to the moon' which was a sci/fi film. This does not fit Bezin's description of how a realist film should be.
Keaton is very much an expressionist filmmaker; as shown in 'Cops' when a bomb is thrown next to Keaton's character. He doesn't realize it's a bomb at first but a lighter. This doesn't fit Bezin's description of matching reality and is done to create audience pleasure as in the early 1920s, the anarchist bombers were very prevalent in the media at this time so the 1922 audience would off been very familiar with the anarchists bombings as just before this was shown, the anarchist bombers who had been behind the 1920 Wall Street bombing were arrested. In the exaggerated chase sequence, every cop in town is chasing Keaton through the streets. This is both a mix of expressionist and realism as it isn't realistic that a short man like Keaton wouldn't be caught by the comedically large number of cops who are all represented as stupid, useless and pathetic as they don't see Keaton escape into a building two groups of cops ran past. However, it is realistic in the sense that the cops would be chasing Keaton who they think is an anarchist bomber. The representation of women in 'Cops' is not as progressive as in his other films as she plays the romantic interest who would only marry Keaton if he is a businessman. Once again, there is no editing and the police chase is in frame the whole time. Other realism films in the silent era were the Lumiere Brothers 'train pulling into the station' sequence. His stunt in 'Cops' make him an expressionist as Keaton's creative signature was that all his stunts were performed by him. The stunt in this film was when Keaton was shot up in the air and it cutted to Keaton falling on a passer-by. This does not fit in Bazin's description of realism due to it being an edit and was done for audience response. Expressionism is used in 'Cops' when Keaton tries to communicate with the horse by using a telephone. This is an example of modern technology being implemented into Keaton's films.
In conclusion, i still believe that Keaton's films are more expressive than realist but his lack of editing and the representation of police matches reality does make Keaton a realist filmmaker in some aspects.