I agree with adding this close reason as it better highlights why this type of question is closed rather than a generic "off-topic, see the help center" message. We have had a few questions on meta about scope and consensus seems to be that we don't want to have questions like this (Should pseudoscience questions be closed on sight?).
My thoughts are not to apply this close reason to questions that are curious but have the wrong initial thoughts that we can address. I am also not meaning to apply this to potential new theories that have evidence, are controversial but don't have full mainstream support (plenty of our current best theories have been in this phase before).
I am instead targetting those questions actively pushing nonsense physics and, who rely on links to blogs and self-published books for all "evidence" that supports them.
The physics close reason is:
We deal with mainstream physics here. Questions about the general correctness of unpublished personal theories are off topic, although specific questions evaluating new theories in the context of established science are usually allowed. For more information, see Is non mainstream physics appropriate for this site?.
We could adapt this by changing the link to a local meta question. From theirs:
Is non mainstream physics allowed here?
No, questions and answers about non mainstream physics are not allowed here.
We are not a substitute for peer-review, and cannot evaluate new theories. While some questions can lead to legitimate new theories, the question will need to be specific in order to fit this format.
What defines mainstream physics?
Mainstream physics is physics which has been accepted by a significant portion of the physics community. In the case of modern physics, if a theory has not been published in a reputable journal, it is not considered mainstream.
What sort of questions and answers are disallowed by this policy?
Any post that attempts to work within the bounds of what we have determined to be "mainstream physics" is considered on topic for this site barring any other issues. For example, a question that proposes a new concept or paradigm, but asks for evaluation of that concept within the framework of current (mainstream) physics is OK. Similarly, a wrong answer that makes false statements but claims to work within the bounds of a mainstream theory is also allowed.
On the other hand, if a question or answer uses a non-mainstream theory as its premise and attempts to go forward in that direction, it can be safely closed or deleted.
I agree with the above take on the issue from physics.se and would be happy to implement it here.