Error in MarketPress when using as Multisite but with main site having Listings Only (i.e. disabling

I've been building a MarketPress network where only one of the sub-sites has the full cart enabled, all the rest, including the primary/main site have 'Product Listings Only' set on. The problem I had was when trying to manage the settings for a payment gateway on that one sub-site, as no allowed gateways were showing. The reason why was that no gateways had been allowed via the MarketPress Network Admin screen. But on the Network Admin screen no gateways were showing because the main site had 'Product Listings Only' set.

Even though the Network Admin screens are 'within' the primary/main site of WordPress, the full MarketPress plugin must load regardless of that sites settings.

I fixed this by changing line 362 of marketpress.php (v2.1.5) from
if (!$settings['disable_cart']) {
to instead read as
if ( is_network_admin() || !$settings['disable_cart'] ) {

As I am still developing this site/network I am unsure if there are further multisite considerations.