The second master who is always looking at the security cameras need dr.Seok for his own gains. Also dr.seok was talking about meeting the serpent, who also wants him for his own gains. Annnnd also arresting dr.Seok and hiding him was a way to make sure he stopped investigating to get himself in more trouble
ohh okay wait but was dr seoks arrest official??
Major is MP controller meaning he got the authority to arrest anyone he wants so technically, yes, but he went against the higher ups with that decision. Notice how second master wanted his position as MP controller revolked? meaning he didn't like that he did that but Major had the authority to anyways
ohh thank u
like in ch61 when he found the binary code in dr seoks room and was all up like im gonna arrest u but then he actually hid dr seok away but it turns out the higher ups dont know what dr seokwrote? otherwise they wouldnt be okay with him "going to gwacheon"as expressed later in ch 71? sorry im so slow lOL