In December 1940 the raider Atlantis holed up at Port Couvreux (49°16'49.25"S, 69°41'19.26"E) in the Kerguelen islands, about 1000 NM north of Antarctica, to refill with water, do some work on its engines, etc. It is unlikely, but perhaps just possible, that some other hideaway near Antarctica (it's not spelled "Antartica", by the way) or maybe even on its coast was briefly used at some point as a U-Boat rendez-vous, refueling point or something of the sort, and maybe the crew went ashore and left some evidence of their visit. But it is indeed absurd to suppose that the Germans had a full-fledged base in Antarctica. It would be impossible to hide, impossible to defend, impossible to keep supplied and too far away from Allied shipping lanes to be of operational value. Furthermore, if there had been such a base and it had somehow escaped Allied notice during the war, it would have come to light long before now and everyone would know all about it. To put it another way, if it was a bit wacky to look for intact buried Spitfires in Burma it would be absolutely insane to look for U-Boat bases in Antarctica.
By the way, regarding the statement that "The man was looking for investors to back him and had a submarine lined up to make the trip.", why would one need a submarine to find the alleged Antarctic base?