The individual referred to as a "trustbuster" in the context of the 1902 Coal Strike reading is President Theodore Roosevelt.
Why is he the trust buster
During his presidency (1901–1909), Roosevelt became renowned for his efforts to combat the excessive power and monopolistic practices of large corporations, particularly those involved in trusts or monopolies that were seen as detrimental to fair competition and consumer interests.
Roosevelt vigorously enforced antitrust laws and took legal action against monopolistic trusts, earning him the nickname "trustbuster."