From recent comments here, it seems there are suspicions and conspiracy theories circulating in Poland based upon extrapolations from the circumstances of, and response to, this accident. This is unsurprising given the human emotions and political tensions, but absolutely unsupported by any sound rationale or evidence.
It seems uncontested that the pilots were offered a clear and sincere entreaty to divert. Given the sensitive and diplomatic nature of the mission I'm sure the Russian authorities preferred not to 'forbid' landing to the Polish President or 'insist' his pilot take a certain course of action. The evidence suggests they wanted the plane to land safely and clearly expressed that this could only be ensured by diverting. What's more, given the conditions, it surely shouldn't have taken a great deal of explanation to spell out to the pilot the inadvisability of proceeding.
Whatever the speed or nature of the subsequent crash response by Russian authorities, there seems nil likelihood that any faster or better resourced emergency response would have saved lives.
Whatever ones' overall feelings about Putin et al, it doesn't take much stropping of Occam's Razor to leave them looking very peripheral to this incident...