It was not uncommon for pro gamers who signed a contract to have some restrictions set in place when it came to joining an organization. However, in the case of Niflheim, the limits were much more significant. This was due in part to his position as a Captain of Blue Oasis. But, the foremost reason had to do with the sensitive information he possessed as the leading strategist for Blue Oasis.
If Niflheim were to go to another top guild, Blue Oasis would be at a considerable disadvantage when facing them in the future. To prevent this from happening, top guilds such as Blue Oasis made it so that players like Niflheim had to wait for two years before joining a different organization.
While two years did not seem like a long time, it was just as Niflheim stated—a death sentence for pro gamers who were in their prime like him.