Slow Pitch Ruling

[whiskers_ump]

Gentlemen,

Since I do not do much, {none in 3 yrs) slow-pitch,
have the following that happened the other nite while
I was watching a co-worker perform. (Co-ed)
I noted that the team that co-worker was playing
against had back to back males batting in the line up.
Watched a little closer and realized that they had an
eleven (11) person roster. They were taking an out
between the two males.
My question is, should this game have even started
with this format? I understand playing shorthanded,
but since co-ed plays with 10 M/F ratio split evenly,
can you legally begin a game with only one EP and
take an out in the other position? Friends team did
protest the game after asking me (he knows I umpire)
if this was a legal move. I said I did not think so,
but did not have book with me. Told them I was not
paying the protest fee if I was wrong either.

Thanks