I do tend to agree with this. Or more importantly it is the DfT's idea, rather than the Government directly. The Government can be thrown out, DfT officials cannot, so policies just carry on regardless of the party in charge, unless the political party in charge actually has someone as Transport Secretary / Minister who knows what they are on about and has the balls to tell the DfT civil servants to change direction. Since privatisation in 1996 this appears to have singularly failed to happen.
Also worth remembering too that the general public at large don't support prolonged striking, especially in public transport and things which inconvenience them. Nowadays they dislike the left wing rabble rousing rhetoric of the RMT press office even more than ever. Any strikes now, would likely go on for a long term, which could actually play right into the DfT's hands. By time Northern actually get round to introducing DOO then the striking guards will be skint and won't be able to afford to carry on striking and the public will be so utterly annoyed with it all they won't care what happens to the guards anyway.
Furthermore, I am not entirely sure what going on strike will achieve. The DfT quite clearly will not change its mind. If rafts of strikes in the South won't change the minds I am not sure how strikes in the forgotten North will do, unless they are thinking ahead to the next election and all those marginal seats, but by then there will no doubt be more important things for people to worry about. Northern have a franchise agreement that a) compels them to introduce DOO on a minimum of 50% of franchise mileage and b) covers their costs and any losses incurred by industrial action. So they, like Southern, have nothing to loose.
And Finally, don't forget that Rail North helped to specify and choose the franchise, and Rail North have a considerable oversight and say in what goes on. It may have escaped everyone's notice that 8 of the 11 Directors of Rail North are Labour Councillors, so Labour councillors helped to specify and choose the franchise.