[basic.scope.temp] p2 says

Each template-declaration D introduces a template parameter scope that extends from the beginning of its template-parameter-list to the end of the template-declaration. Any declaration outside the template-parameter-list that would inhabit that scope instead inhabits the same scope as D.

Since we have said that the template-declaration D introduced a template scope that is extended to the end of D before we state the second sentence. According to [basic.scope.scope] p2

A declaration inhabits the immediate scope at its locus

Consider this example

template<class T>
struct X{};

The locus of the class-specifier is immediately after X, that is, the locus of the class specifier is contained by the template parameter scope. This makes what scope D inhabits ambiguous. The intent is to say that D inhabits the global scope. The improvement might be:

Each template-declaration D introduces a template parameter scope P that extends from the beginning of its template-parameter-list to the end of the template-declaration. Any declaration outside the template-parameter-list that would inhabit the scope P instead inhabits the same scope as that D would inhabit if the scope P were ignored.

Or, we can just say

Each template-declaration D introduces a template parameter scope P that extends from the beginning of its template-parameter-list to the end of the template-declaration. D inhabits the scope S after ignoring P. Any declaration outside the template-parameter-list that would inhabit the scope P instead inhabits S.