Teleporting in general does release a creature from a conjuration such as tanglevine, however, Blue Gremlin specifically states that when he teleports when he moves. This is still considered a move action, which the restrained trait specifically says you can not do.
As well, a crippled Gremlin may not take a move action. All his ability means is that if he does take a move action that turn, each move counts as him teleporting into that zone. It is still a move action, which, if the creature is restrained, it cannot do.
As well, this is what hinder states:
Hinder
If a creature begins its Action Phase in a zone with any
enemy creatures, or enters a zone occupied by an enemy
creature, it is hindered. A hindered creature may only move
1 zone during its Action Phase (even if it has the Fast trait).
Incapacitated, Restrained, or Pest creatures cannot hinder
movement.
This means that the Gremlin is still hindered by the enemy, as it's "teleport" ability is specifically a move action.
I hope this helps you!