MLF is NOT recommended for wine kits (concentrates & juices) as they contain a higher proportion of malic acid than grapes (or fresh fruit) - a result of the different processes they go through.
If MLF were to occur, the high proportion of malic acid would be converted to lactic resulting in a wine with very little acid and a pH probably above 3.8. Leaving it weak (flat), soft, and vulnerable to bacterial infections and spoilage.