This is a Prime Minister and government obsessed with optics and imagery. "Global Britain", whatever that means (I think any continent except Europe) targets India and his fellow populist leader Modi. A PM with a reputation for dithering , dithers about closing the door to India as the same time as Pakistan and Bangladesh. In that time over 20k people come to the UK and the Indian/Delta strain dominates.
The idea that Johnson would visit a country that his government had just placed on the red list, regardless of his perceived right to do so is for the fairies. Even the Mail would have hammered him. It's not rocket science.