Not really, it's better than nothing, but not by much, whereas MJK's Classic TL design routine is the 'real deal'. IIRC it use to be online at your linked site, but for whatever reason it was left out of the all new site.
GM
edit: That said, this will calculate a real Voigt pipe, i.e. a [tapered] TL with no separate vent, though of course one can be added to tune it lower if desired [ML-TQWT] whereas your link is a horn tapered ML-TQWT [aka ML-horn], so either make a Voigt pipe tuned to Fs or one tuned up around 1.4-1.56x Fs and vent to whatever works best overall in room.