functions.php

<?php
/**
 * Hide empty editor on posts
 *
 */
function ea_hide_empty_editor() {

	$screen = get_current_screen();
	if( $screen->id !== 'post' )
		return;

	$hide = true;
	if( isset( $_GET['post'] ) && !empty( get_post( $_GET['post'] )->post_content ) ) {
		$hide = false;
	}

	if( $hide ) {
		remove_post_type_support( 'post', 'editor' );
	}
}
add_action( 'admin_head', 'ea_hide_empty_editor' );