No. Certain websites promise to provide large numbers of likes for your Page if you sign up and give them money. These websites typically use deceptive practices or are scams. People who like your Page this way will be less valuable to your Page because they won't necessarily have a genuine interest in what your Page is about. If Facebook's spam systems detect that your Page is connected to this type of activity, we'll place limits on your Page to prevent further violations of our Statement of Rights and Responsibilities.
So, I suspect that by "safe" they mean they haven't gotten caught by the site spam prevention systems.
Facebook's spam detection systems will automatically place limits on your Page if they register suspicious or deceptive activity that violates our Statement of Rights and Responsibilities.
For example, your Page may get unpublished for promoting spam, or the Like button may get disabled for deceptively acquiring likes. These limits apply to activity coming from your Page, not for posts other people make on your Page.