There have been easter eggs that have been discovered years after the product has been released. The fact that it wasn't found in the code is irrelevant since it can be encoded and rewritten to not be found. The code for another step could be hidden in the team deathmatch protocols for example. Unless you take apart every single line of code, you can't be 100% entirely sure.
And then there's always a chance that more steps will be added in the future with an update. Some people say oh they can't do that..... why not? It's very simple. They provide us the first few steps now and then will give us some more later if they desire.
That said, every player receiving a very powerful gun for 90 seconds sounds to me like the end of an easter egg, so unless some valid proof of this website can be given, I'm inclined to believe that the end of the egg has been found.