What Does Montresor accomplish by praising Luchesi as a good judge of wine?

Edgar Allan Poe's short story, "The Cask of Amontillado," is the tale of Montresor describing his revenge upon Fortunato, who insulted him. His family motto is "Nemo me impune lacessit," which is Latin for "no one insults with impunity." To accomplish his revenge, he plans to lure Montresor to the catacombs that lie beneath his house. In these catacombs, where the bones of his dead ancestors repose, he keeps a wine collection. He intends to lure Montresor to the lowest depths of these vaults and wall him in, burying him alive, where his cries for help will never be heard. 

In order to lure him to the vaults, Montresor finds the inebriated Fortunato at carnival. The story is set in Italy. Montresor describes Fortunato as a man worthy of respect, but Montresor finds his weak point and exploits it. This is one thing Montresor accomplishes by praising Luchesi. 

"He had a weak point, this Fortunato, though in other regards he was a man to be respected and even feared. He prided himself on his connoisseurship in wine. Few Italians have the virtuoso spirit. For the most part their enthusiasm is adopted to suit the time and opportunity--to practice imposture upon the British and Austrian millionaires. In painting and gemmary, Fortunato was, like his countrymen, a quack--but in the matter of old wines he was sincere." 

When Montresor greets him at carnival, he tells him he has received a cask of Amontillado and has his doubts about whether it is genuine. He tells Fortunato he has paid the full Amontillado price and asks Fortunato to come and see if he's been swindled. In order to entice him to come, he tells him he could ask Luchesi instead since Fortunato is presently engaged. This pricks Fortunato's pride, which is Montresor's intention. Fortunato says that Luchesi is no expert and agrees to go with him. 

As they venture into the vaults, Montresor continues his offers to consult Luchesi instead. He is toying with his victim like a predator toys with his prey. This is the second thing he accomplishes by praising Luchesi.  When Fortunato begins coughing, Montresor feigns concern and offers to go back in order to save his guest's health. He says:

"We will go back. Your health is precious. You are rich, respected, admired, beloved; you are happy, as I once was. You are a man to be missed. For me it is no matter. We will go back. You will be ill, and I cannot be responsible. Besides, there is Luchesi--" 

Montresor knows that Fortunato will continue at the threat of consulting Luchesi instead. He has no true concern for Fortunato, as he is about to kill him.