Whilst that kind of makes sense. You are forgetting the fact that the £120k is inclusive of a type rating. Yes you may pay less to be on a standard whitetail but you will still end up paying for a type rating at the end of it (provided you don't get a job with an airline that pays for a type rating).
You sign a conditional offer of employment, just the same as route 1 & 2, on route 3. It is certainly a safer route that a standalone whitetail route.