Why do Conservatives keep denying that an investigation is needed in the Yellowstone River Oil Spill so that?

the American People can know if that spill was the result of Exxon themselves -wanting to get back at the government for threatening to take away subsidies by despoiling one of our national parks and scaring up the price of oil on domestic exchanges by spawning fears of a supply disruption- or whether this was the work of a far-Right anti-Environmental fringe group?