Hey splash
Seriously, I believe that it is not something that I would count on to flush the outboard efficiently. As it is only cold water going through it, but when you put the flushing muffs on you have the motor running. And will get the heat into it, to help to get the salt out.
I do have the same fitting on my Yammie, it is good for when you get home late so you don't make to much noise.
dave