I am not sure if Lo Wu Station has been under renovation. Even so, its closure should not be related to the renovation.
Currently, all Hong Kong Control Points are open except Hung Hom (MTR ITT - expected to be permanently shut down), Lok Ma Chau (non-MTR - currently closed due to Huanggang Port renovation), and Lo Wu.
I believe it has more to do with the East Rail Line cross-harbor extension to Admiralty instead. Since the service extension, East Rail Line is running from 12 cars to 9 cars. East Rail Line has not been under stress for 3 north-bound terminus (Lok Ma Chau, Lo Wu, Sheung Shui). I believe MTR wants to take it slow instead of stressing the line.