You'd have to ask a Shafi'i for this. For your quotes, they may have been cited by a non-Shafi'i. Many times, some Shafi'i ulama may be cited to show one side of the story but it may not be representative of the madhhab. Another issue that is given a similar treatment is the issue of the beard, where non-Shafi'is end up quoting some Shafi'is who held beliefs about the beard that were not the contemporary mu'tamad opinion of the madhhab. Similarly, some Hanafis, in their effort to legitimize things that are clearly forbidden in the Hanafi madhhab resort to referring to a small minority of Hanafis but largely rely on the opinion of non-Hanafis. This is the case with this very issue of building over graves, which is forbidden in the Hanafi madhhab, but some people try to legitimize it by referring to minority opinion in the madhhab or to ulama outside of the madhhab. Salafis in general should not really have a problem with this difference of opinion, though, since there are varying differences of opinion among the Salafiyyah as well. Another controversial issue that comes to mind (upon which there is almost unanimous agreement as to its prohibition) is touching ghayr mahram women - and Yasir Qadhi doing this by shaking hands with some Egyptian woman. This was followed by people defending him and justifying his act by citing minority opinions.