Time_wait - why so short?

I am not sure why F5 picked 2s but having a lower time_wait state will enable quicker shutdown of the sockets and hence, will enable the creation of more TCP connections within a specific time window. Basically, it increases the ability to handle higher scale (more connections within a time window).

The time_wait of 2 minutes works when the internet was in its infancy - slow and smaller scale. This doesn't work well for the scale and speed of modern internet.

time_wait usually helps in making sure that there are no delayed packets/duplicate packets for a TCP connection that is closed and could be interpreted as part of a newer TCP connection.

For the question on why 2s and not say, 4s - I am not sure.