Hi andydd,

I already did release the changes to the original script. The extension is not a closed source project but open source.
Regarding background requests:
The extension does not perform any background requests without user initiation (click on the link/button).
At the moment there are two possible requests: GCM and WhereToCredit. I removed all Farefreak requests, as FareFreak seems not to be continued anymore.

Unlike backend applications like BookWithMatrix it is not possible to perform background requests in an extension without the user being able to notice, as everything is done in your browser (not on an external server).
Just open chrome's developer tools and check the network tab:

Here you can see the request to wheretocredit, when you click on "Calculate miles with wheretocredit.com".

I created the extension with modern frameworks and tools because I used it a lot and it was a hassle to maintain the script in one single file and load it into my browser.

It's still an open source project everybody can contribute to, but without the hassle of loading the js-script in your browser and with automatic updates.