Those offices are usually locked down anyway, on floors where the unwashed masses aren't granted access. Hell, if you want to even be on a call with someone like the CTO you'll have to reach out to three different entities, book a specific room, and reach out to that person's team of assistants to ensure everything is aligned.

If they got access to the CTO office they definitely broke in, or evaded security in some way. That alone at any company will get you fired, and probably arrested.

Source: Once attended a meeting with a SVP at a big tech company. I genuinely think it would be easier to meet the president.