You think they would move that new station interchange along so cov could benefit from HS2 .
I agree, but the argument has always been that in order to gain the time saving further north it has to have few stations in the south. They then say that having the HS2 interchange by the airport and getting a train from Birm Int would be equivalent but misses the point that it's inconvenient having to swap trains and is no quicker than the ordinary WCML service.
I'd be fine with that IF it was just having one stop at the interchange but the fact it's getting a dedicated central Birmingham stop, with the extra cost of creating a spur specifically for it blows that out of the water and shows they're willing to make exceptions if it suits them.
Like you I'd still place the station close enough to provide an argument and enable a connecting service in future if we lobby long enough for it.
I'm still of the opinion that HS2 is there to increase London's airport capacity and will largely be used for carrying passengers from BHX to London and back. One the first section is built I fully expect the next stage to be canned as suddenly they'll decide the business case doesn't add up, even though it hasn't for quite some time and the costs keep escalating.