I highly doubt that the man rotting in MC's home is his father. It was the robber ML killed from the prologue. His body was just rotting there and MC was so out of it that he forgot he was even gonna get robbed until MC saved him and took him in.
So Guwon was probably saying the truth in the previous chapter, MC had something to do with his father's death that made him forget all that shit.
I highly doubt that the man rotting in MC's home is his father. It was the robber ML killed from the prologue. His body was just rotting there and MC was so out of it that he forgot he was even gonna get robbed until MC saved him and took him in.
So Guwon was probably saying the truth in the previous chapter, MC had something to do with his father's death that made him forget all that shit.