Stat is made negative by the word non.
However, the resulting sentence, In medio non stat virtus, is rather uninformative.
'Virtue resides in the mean' is a pregnant saying: it sums up a philosophy.
'Virtue does not reside in the mean' merely negates a proposition, without offering anything positive.
Virtus a medio remota (est).
Are you saying that you read 'lies' as a pun between 'rests' and 'speaks untruth', and you want to reproduce that pun in Latin?I intend to say exactly what it means in English (it is not true that virtue lies in moderation; it will sound like a pun in the context and that is what I need)