"Johnson even chooses to defend the Tories on immigration, saying they represent a 'mainstream, centre-right' party engaging in a 'decent, centre-ground debate on immigration'. This, despite the Tories having stuck to the 2005 pledge, under Michael Howard, for an immigration 'cap', which - along with campaign posters asking 'Are you thinking what we're thinking?' - led to accusations of 'dog-whistle' politics."
It's a truism that in order to have a sensible debate, you've got to be willing to actually have a debate – so it's encouraging that Johnson is taking this more conciliatory approach to the question of immigration. And it also reflects well on him, as you suspect some of his more tribal government colleagues (and there are plenty of them) would have dealt with the question differently. All in all, you can chalk it up as more fuel for John Rentoul's AJ4PM campaign.