While it is entirely likely that they will issue an FAQ or errata to clarify this issue, I would not count on it. The same question arose in Brett armies with respect to the ability of a character on a peg joining a unit of peg knights.
In the Brettonia FAQ it says: "Q: Can a character riding a Royal Pegasus join a unit of Pegasus
Knights? (p55)
A: No." So, that implies that until an FAQ or errata changes that ruling, neither Tik, nor a skink chief of a ripper or a terradon, can actually joint a unit or rippers or terries. This prevents them from lending their leadership to those units and gaining a full look ou sir and the allocation of BS shooting hits from the unit.
Given the ambusher special rule ability, I suspect that GW will at least allow Tiktaq'to to over-ride the skirmisher special rule provision that a character on a mount cannot join a unit of skirmishers (BRB, p. 77). But, given the disappointing Bret FAQ ruling, I would not count on a favorable ruling wrt to skink chiefs on terries or rippers being able to join with terry or ripper units even though it is obvious that they should be able to join those units (same exact type and special rules of flying cav and monstrous cav) and it would improve those units without making them OP. As it is, I thinik terries are generally not worth playing with a cost increase and low LD. A unit of 3 or 4 terries loses one to magic or shooting and the entire unit fails the panic test almost half the time. At least rippers have frenzy, so they don't panic but might be at risk of being baited and have a hard time holding.