As users it is not our job to police the content on this site in order to ensure that it conforms to every possible jurisdiction (this is, after all, an international audience). It is even less so our job to enforce the licenses and terms of service of some unrelated third party.
In section 3 “subscriber content” of the SE terms of service, we do however agree that:
Subscriber represents, warrants and agrees that it will not contribute any Subscriber Content that
(a) infringes, violates or otherwise interferes with any copyright or trademark of another party,
(b) reveals any trade secret, unless Subscriber owns the trade secret or has the owner’s permission to post it,
(c) infringes any intellectual property right of another or the privacy or publicity rights of another,
(d) is libelous, defamatory, abusive, threatening, harassing, hateful, offensive or otherwise violates any law or right of any third party,
(e) contains a virus, […], or
(f) remains posted after Subscriber has been notified that such Subscriber Content violates any of sections (a) to (e) of this sentence.
(formatted for better legibility)
Noting the existence of Hackintoshes certainly does not violate Apple's rights.
Whether suggesting that another user could build a Hackintosh is illegal or not depends solely on the jurisdiction you are subject to. Private contracts such as terms of services are not law, so breaking them or suggesting to break them is not usually illegal, though possibly unethical. However, copyright infringement or circumventing DRM is often illegal.
If based on your knowledge of building a Hackintosh and based on your applicable jurisdiction you feel comfortable writing such an answer, then please do write that answer.
If based on this knowledge/jurisdiction you do not want to write that answer either because it would be illegal or because you consider it unethical, then don't write that answer.
If you see content that you wouldn't have posted, assume that the poster wrote that answer based on their knowledge and jurisdiction which is likely to be different from your situation. You can vote as you please, and if you want leave a comment that explains how the answer applies to your jurisdiction.
It is not your job to enforce the rights and contracts of third parties, and in particular not your job to enforce the SE terms of service against other users. If a post is in blatant violation of the SE terms of service or of the community standards, then raising a flag may be an appropriate action – but please don't do that for cases that are on the fence like “possible suggestion to violate the terms of service of an unrelated company that doesn't even enforce its ToS in this situation”.