If it were me, I would not do this.
DTD buses are notorious for being the least reliable. They seem to take longer to arrive at either end - I've timed them at 45 minutes between buses many times. I would be concerned about being on time for the meeting relying on Disney transportation, unless the meetings started late morning or in the afternoon.
However, once at DTD, it would take maybe 15 minutes or so to get from the Marketplace stop to the Wyndham, depending on how long you had to wait for the light to cross the street.