He didn't say he was making a Saison Dupont clone. He said he wanted it a little like it. Which I interpret as "inspired by". It's quite possible that he will use the dupont yeast, in which case you're correct, you do need to ramp it up quite warm to get it to attenuate, and probably leave it there for a couple weeks. That yeast is notoriously stubborn. Of course if he's not in fact using that yeast, as was the conclusion you jumped to, then all bets are off until we know what he is in fact using.
And if you can't get a Saison to dry out using an all malt grainbill then you are either A, having fermentation issues, or B, only make strong saisons. I personally prefer a lower gravity saison and it's quite easy to get an all malt grainbill in the 1.040s to finish at or below 1.005 without sugar. Usually a long and low single infusion mash is all that is necessary. If, on the other hand, I am trying to make something stronger, then sure, simple sugar is the way to do it and still have a dry product. But it's far from a requirement in every Saison brewed.
As for the grainbill, it's a saison dude, not a Helles. There are no laws dictating what grains can and cannot go into it. By it's very nature saison grain bills can be all over the place. While mostly pils with a touch of vienna can make a great saison, it is far from the only way to make one. What about wheat? Or spelt? Both being very traditional grains used in these beers. This is one of the styles that I feel the BJCP is really doing a disservice to, by trying to pigeonhole it into what they think it should be - ie, Saison Dupont.