I think it's totally fair that Shopify would release it on Github and little too harsh on them since most of the companies are doing that! So what Ryan is saying makes total sense.

Having said that Sarah's points are valid too since most of the Shopify's users are non-technical. They wouldn't want the hassle to update the plugin or wouldn't know if the update is available on Github for their WordPress install.

Lets agree that both of you are right :) Peace!