Preheat the oven to 375 degrees F.
For the lobster: Bring a pot of water to a boil. Remove the lobster tails from the shells and put into the boiling water. Poach for 2 minutes. Remove the lobster and set aside to cool.
Once cooled, chop the lobster and mix with the lime juice, cayenne, seafood seasoning, and mascarpone. Taste and add salt, if needed.
For the chowder: On a sheet pan, toss the corn kernels with a few tablespoons oil, season with salt, and roast until the corn is lightly browned, 8 to 10 minutes.
In a deep pan, heat 1 tablespoon oil over low heat and add the bacon. Cook until the bacon is crisp. Remove the bacon to a paper towel and pour most of the bacon fat out of the pan.
Return the bacon to the pan, add the onion and celery, and cook over medium heat until the onion is softened, about 5 minutes. Add the red and green pepper, garlic, and roasted corn, and cook 5 more minutes.
Sprinkle the flour over the vegetables and stir. Cook for 2 minutes, stirring constantly. Add the chicken stock and stir to scrape up any brown bits from bottom of the pan. Stir in the diced potatoes and raise the heat a little to bring the mixture to a simmer.
Simmer the chowder until the potatoes are cooked, about 20 minutes. Stir occasionally to avoid burning the bottom of the chowder.
Taste the potatoes. When the potatoes are fork tender, turn the heat down to low and slowly stir in the cream. Keep warm on low heat.
To plate: Ladle the chowder into bowls and top each with a mound of lobster. Garnish with sliced scallions.