The mountain is long but the first half is very flat and only the final less than 10km is really steep, so it isn't a pure climbers climb. The cobblestones are set to easiest level as well.

The cobblestones work as more of a foil for the climbers then a determining factor, pure climbers make attacks but are brought back by domestiques for both cobbled terrain and climbers, the first test I did had Valverde, Quintana and Porte as the three best climbers (let the AI select teams and they mixed between cobbles and climbers), Porte won, ahead of Quintana, then Amador then Valverde, however less than 1'30 later a 30 man bunch contested the sprint: Wellens was 5th, Kwiatkowski 6th, Devenys 7th (73mo, 74cb or something), Alaphillipe 8th, Ullisi 9th (who did a lot of domestique work and is below 65 in mo and cb so strange ) and Pozzato 10th. So it really was more a mixture of climbers and cobblists.

The second test I picked teams, with the best 4 climbers and best 4 cobblists from each team. Barguil (77mo) joined the break and Valverde, Rodriguez, Quintana and Nibali attacked before the cobbles but were caught and for most the climb, Wiggins (74mo, 78cb) pulled back every attack with Froome sitting behind him although with about 3.5km to go Nibali and Valverde got away and sprinted out the win (won by Nibali). In the main group they had about 20 riders with 2km left and Froome had been dropped, when Devyns attacked (73mo,74cb) and was followed by Rodriguez, who couldn't even keep his wheel and hit the wall, letting Devyns finish 3rd, although Rodriguez still came 4th. In the group (still 20 riders at the finish) Visconti (73mo,70cb) and Amador (78mo,71cb) got 5th and 6th ahead of Van den Broeck, Hesjedahl, Geniez and Schleck with Wiggins, Quintana and Contador finishing 12th, 13th and 14th.

tl;dr: It works as a climbers race where the cobblestones make it hard to get away and can advantage riders who can climb and cobbles (Devenys )