In the examples, Tygal's correctly using the feat Shaping Focus, but Nazghymbatulu isn't because the saurian shaman druid archetype delays Naz's wild shape ability until he's at least a Drd6.
A druid with the special ability wild shape who takes the feat Shaping Focus increases his effective druid level by up to 4 for the special ability wild shape but not beyond the creature's total character level
Thus a typical Drd4/Ftr3 who takes the feat Shaping Focus employs the special ability wild shape a if the Drd4/Ftr3 were a Drd7. (I chose the Drd4/Ftr3 instead of Drd4/Ftr4 because in typical campaigns the latter character wouldn't have a feat available at that precise total character level.)
However, the feat Shaping Focus can't benefit the saurian shaman Drd4/Ftr3 who, because of his archetype, until he reaches level 6 as a druid, lacks the special ability wild shape:
At 6th level, a saurian shaman’s wild shape ability functions at her druid level –2. If she takes on the form of a reptile or a dinosaur, she instead uses her druid level +2.
Prior to 6th level, then, a saurian shaman doesn't have the special ability wild shape. Therefore a saurian shaman Drd4/Ftr3 is unable to meet the prerequisites of the feat Shaping Focus and can't get the feat's benefits were he able to somehow.
Likewise a creature with no druid levels that somehow managed to take the feat doesn't gain the special ability wild shape as if the creature were a level 4 druid.
By analogy, the feat is like a coupon for extra 4 toppings on a pizza; one must still buy a pizza to get the extra toppings.