Katie Cook does it again, ladies and gentlemen.

This is absolute, unmitigated nonsense. Twilight's used magic on other people, even her friends, plenty of times over the course of the show and comics. The cattle rustlers are criminals who are actively harming her friends and the townsfolk as well as destroying property, and she's not lifting a damn hoof to help because of some hypocritical moral high ground?

If all Twilight's going to do is arbitrarily make life hard for her friends on account of some moral code she decided to pull out of nowhere, then why is she even here? They could've just left her out of this arc entirely and avoided this problem altogether. Have her go with Spike to Las Pegasus for his Trekkie convention. Spike gets some company, and no characters are destroyed in the process. Everyone wins.

Imagine if Twilight tried to help with magic, but Applejack refuses out of a desire to settle things "the old fashioned way". She's known to be incredibly stubborn when her pride is wounded. That also would've been acceptable.