Don’t think you are being a pedant - just goes to show that they aren’t stating things well or consistently. I’m quoting from the latest pre-order page on Warhammer Community: https://www.warhamme...-space-marines/
I hate to be the pedant in the group (actually I love it, but it's beside the point...), but in the WHC article on 15th January it states that Lazarus is "the first-ever Primaris member of the Inner Circle."
This could just be because the guys writing the WHC articles aren't as 'hot' on Dark Angel lore, and there was an editorial slip on the terminology used, but when I first read that article I was both confused and annoyed. If it turns out they meant first to cross the Rubicon, then I'm perfectly happy with that.
Psychic Awakening: Ritual of the Damned also sees the arrival (in model form) of Master Lazarus – the first-ever member of the Inner Circle to cross the Rubicon Primaris.
So yeah - WHC editing at its finest. Guess we have to wait on the book to see what it actually says (and hopefully it’s not yet another permutation on the concept).