Is it always assumed that theme forces are limited to faction only?
If Khador had a theme force that allowed medium based units, would Boomhowler and Co. be allowed in that theme force? It is a medium based unit that will work for khador. Obviuosly it's not a khador unit. Unless khador is a key word.
If not, then why make a stipulation in theme forces that state 'khador heavy warjacks only' or 'khador non-heavy warjacks only'. Why not simply state 'heavy warjacks only' or 'non-heavy warjacks only'.