A couple of points...
First of all, I'll admit my source of information was wikipedia, on the basis I couldn't be bothered to look any further!!
Tupolev Tu-22M - Wikipedia, the free encyclopedia
Apparently the Tu-22M was produced from 1967-1997, with none exported (so far), although on the break up of the Soviet Union some of the lesser states ended up with some of their own.
Anyway, are these Chinese ones new built, or Russian ones handed over? Presumably the latter? It would appear that the Tu-22M production line hasn't been used to build aircraft for at least 15 years, has been in place for nearly 40 years, and is probably still based on the original 60s or 70s technology.
Can you imagine the engineering issues involved in moving a 40 year old, probably already in disuse, production line several thousand miles and get it going again. You'd almost be better off starting from scratch with the drawings and maybe a few jigs.
I once had the misfortune to be involved in an attempt to recover some equipment that a UK aircraft manufacturer no longer required for an RAF aircraft type that was soon to retire. The equipment in question was still in occasional use, was maintained, but had been fixed in place for about 30 years. When we tried to physically dismantle and move it much of it just fell apart in the engineers hands.
I just think that there are a lot of practical difficulties involved in this reported production line move - a lot easier to say/write than to actually do!