Let's remember that Archer and the human heroes were not particularly interested in issues of "cultural contamination". T'Pol was the one sprouting lines of Vulcan propaganda about this.
Essentially, Archer ordered a communicator recovery mission either to placate T'Pol or simply to get the piece of equipment back, but evidently paid no attention to the impact the lost communicator or the recce or recovery missions would have on the locals. They had been down there once, there'd be no harm in going down there again...
Even after being captured, our heroes seriously consider identifying themselves as aliens from outer space. What holds them back is not concern about "exposure" or "contamination", but mere tactical consideration about whether a lie or the truth would work better in saving their bacons.
Perhaps the communicator could have been beamed up after a few days of additional sensor work or something. Archer just didn't want to go to that trouble when the simpler option of going to get it by hand was so readily available.