eWay gateway - Will it work for non-multisite blogs?

I found this line of code which stops my single site activation of the Marketpress plugin not display the eWay Gateway.

LINE 6367:

if (is_multisite() && !is_main_site()) {

I have a multisite installation, but I am not using Marketpress as network activated plugin.

When I change the line to

if (!is_multisite() && !is_main_site()) {

it works fine as does

if (is_multisite() && is_main_site()) {

even though its not the main site.

I confirmed this when i wrote it just above this line.

if(is_multisite()){
  echo 'true:';
} else {
  echo 'false:';
}

if(!is_main_site()){
  echo 'true';
} else {
  echo 'false';
}

The above returned true:true... yet eWay doesnt show up.

Ideas?

Ben