I don't have my new DSAT manual to hand, but there has always been a requirement to have a technical diver qualification.
The DSAT Tec Instructor rating is a strange one. As I recall from memory (I might be wrong), Tec Instructors can only teach the new Tec40 course. They have to be qualified as a Tec45 diver or equivalent, where equivalent is defined as qualified to conduct staged decompression dives to 45m using twin tanks and oxygen for accelerated decompression.
There is also a requirement for, I think, 20 staged decompression dives.
There may be some confusion of pre-requisites and exit conditions. A person may be allowed to enter the Tec Instructor course without being a technical diver, in which case the Tec Instructor course *must* include additional dives that lead to the Tec45 diver certification for the instructor candidate.
The candidate won't actually become a Tec Instructor until they have gone off and completed their 20 staged decompression dives *and* interned on the delivery of at least one Tec40 course.
That would make much more sense...