I had that same issue, I hit 50, and was back logged with a ton of main ARR storyline to still do. I ended up level 55 before I got to HW. Then the NPC would talk to me again

Sorta stinks they did it that way, but I guess they assumed most people had all their main story done before they launched HW, so they wouldn't have this issue that newer players would, or something!

Good luck with it though, the main story is pretty cool. The only level 50 side quest I picked up was the Hildibrand line for the fluff rewards.