class Rubocop::Cop::Style::Proc

would be more appropriate.
This cops checks for uses of Proc.new where Kernel#proc

def autocorrect(node) 

def autocorrect(node)
  @corrections << lambda do |corrector|
    corrector.replace(node.loc.expression, 'proc')
  end
end

def on_block(node) 

def on_block(node)
  # We're looking for
  # (block
  #   (send
  #     (const nil :Proc) :new)
  #   ...)
  block_method, = *node
  add_offense(block_method, :expression) if block_method == TARGET
end