Googlebot does not interact with the page like a user. It does not click on anything. It does not scroll. If content is loaded into the page when users click, Google is not going to index it as part of that page.
The only reliable way to keep Googlebot from crawling something is to use robots.txt. You could put the AJAX URL itself into robots.txt. Googlebot would still be allowed to crawl the page, but would not be allowed to load the AJAX. So you could use
Disallow: /regulations.json in
robots.txt but still have Googlebot crawl and index
/mypage.html which calls
regulations.json via AJAX.
You can prevent Googlebot from seeing portions of the page like this. It doesn't matter if the content is loaded via AJAX on click, or on document load. If Googlebot isn't allowed to crawl the AJAX URL, Google won't see the content. See Preventing robots from crawling specific part of a page for full details.