I have mentioned Lemmy several times on /r/RedditAlternatives without any issue

• https://old.reddit.com/r/RedditAlternatives/comments/1hmf2uy/is_alternative_social_media_a_series_of_small/m4odk1u/
• https://old.reddit.com/r/RedditAlternatives/comments/1hk6965/found_a_reddit_alternative_thats_kind_of_great/m3f9rsd/
• https://old.reddit.com/r/RedditAlternatives/comments/1fmuk7o/post_to_address_the_usual_criticism_about_lemmy/

Of course on other subs that would indeed get you in trouble