The author says it's too slow and works better as an asynchronous request. They also write something about rails' "User" object being unwieldy, whatever that is.
That still doesn't explain the Twitter dependency. It could just be an attempt to get popular and share the tool at the same time.
I sympathise with this a lot. It's tempting to say "oh just use ActiveJob, and a CAPTCHA to stop bots, and Devise for auth, and MailChimp to let users know it's completed, and build a UI for submitting new jobs, and also for viewing pending and completed jobs", but all those little things add up.
I do have a Twitter account, basically so nobody else can create one with my usual handle, and never use it.
I don't see why I should let Twitter know that I'm using this service. Furthermore I should log into Twitter in a browser tab and go there to check if the result arrived. On the other side I understand that it's hard to find a convenient asynchronous delivery mechanism. Email is what everybody has but it's hard to send thousands of emails for free and not to get into a spam list.
That still doesn't explain the Twitter dependency. It could just be an attempt to get popular and share the tool at the same time.