It is eventually revealed in Spectre that the titular organisation possesses unprecidented levels of surveilance, and it is by virtue of this that Mr Hinx is able to track Bond across the globe.
However, Bond and Swann decide to confront the organisation and are on a train on the way to Spectre HQ when they are attacked by their pursuer.
Why would he do this?
The train is heading to a pretty desolate location, it's obvious that Bond is coming straight to Blofeld. What does Hinx have to gain in attacking/apprehending/murdering the couple on their way?
They have effectively been invited, it doesn't make sense as to why Hinx would choose to attack.