They could, but if they have superior hardware I doubt they'd want to have to support the long tail of Peloton users with existing bikes.
To put it another way: why should Apple buy Peloton? Apple itself is already a premium brand with huge awareness, so a buy for brand reasons isn't that persuasive. Peloton has a whole range of hardware but none of it is compatible with existing Apple hardware, so integration might be a drag.