Zach Thomas may suffer because he played during the same era as a few other really great linebackers (Brooks, Seau, Lewis).
But... his individual career accomplishments are worthy. 7x Pro Bowler, 5x first team All Pro. That's a 5 time first team All-Pro playing the same position as Ray Lewis and Junior Seau when they were still on the field, something that's pretty impressive. IMO that resume easily stands up against recent inductees like Rickey Jackson and Andre Tippett.
I think there will be room for Zach. They found room for Andre freaking Reed.
I don't have many good memories of that era of Dolphins football, but Zach Thomas was a great player. He's worthy.