It would work intially, but a well fed motoro will outgrow that tank quicker than you might think. I don't know specific growth rates, but it is quick.
Depending on the design of the sump, media capasity and its efficiency, you could keep that 5" motoro in a 4x2x2 for at least 6 months... probely closer to a year, maybe more...
Large and frequent water changes are a must though.
My motoros started out in a 6x2x2.5 and my female was about the size of yours
and my female outgrew it in 2 years. However my male is over 3 years old and is still in there.