Contribution saved as eligible although the declaration was negative

In some tests, the extension performed different than I expected in terms of what it saved in the contribution eligibility. A new contact sent a contribution saying no to Gift Aid, this occurred:

• the contact was created and a new Gift Aid declaration is added to the contact record,
• the declaration has a clear no, as expected,
• but the corresponding contribution is created with a yes instead.

This was due to the fact that the contribution will store:

• 1 (yes) if the site has the option "all financial types are eligible for Gift Aid"
• 1 (yes) if the financial type of the contribution is set for Gift Aid eligibility

What I was expecting, instead, was:

• if the Gift Aid eligibility chosen by the contact was 1 or 3 (yes):
  • if the contribution belongs to an eligible financial type, it will store a yes
  • if the contribution belongs to a non-eligible financial type, it will store a no

...and, specially:

• if the Gift Aid eligibility chosen by the contact was 0 (no):
  • regardless of its financial type, a no will be saved

Is this an intentioned behaviour? I haven't started preparing any merge request because I need to make sure I understand first how the extension is meant to work.