There is reason that range is there, above that and you can be torquing the seat tube causing damage that you wont notice until one day it fails, putting you at risk and perhaps ruining your frame.

At a minimum it should extend below the bottom weld of the top tube/seat tube connection. Sure you might get by with it as it is, but I'd recommend being on the safe side, It's not a big deal, just buy a longer seatpost. It doesn't have to be expensive but the consequences of running a too short post might some day be.