The only way I can see anyone asking a scarab in under 5 mins is having two allies constantly tribute cash to him. Even then you could be attacked before it finished or attacked on multiple fronts screwing your allies.
And I should mention that to make it you'd need 5,000 to get both power(if not in a generator thing) and the cost of making the supply depots, bases and temple. I don't think it would work.
Think that new units/leaders/factions are possible or going to be added? Think again, read the linked thread.
http://www.halowars.com/forums/thread/741500.aspx