That conclusion seems like a bit of a stretch to me. From every account that mentions female gladiators they seem to have been organised and fought exactly like the male gladiators - even to the absolute seriousness that the spectators and fighters treated the bout. Yes, I agree that the inscription indicates that both fighters were released but my interpretation is that they earned it - they fought each other to the point of exhaustion and, presumably, were rewarded for their bravery and skill. Also lets not forget that, although they were on the lowest rung of plebiean status (along with actors and prostitutes), these were professional entertainers/performers and, just like with the men, looking attractive was a big part of the job. I see nothing that would indicate these were anything other than professional gladiators in a serious fight.