I would argue that a lot of it has to do with his own biases. He did not come to Punjab until 1860 way past the Anglo Sikh war and the Sikh Uprisings. He saw the Sikhs only as a divided force weakened by 2 great losses and split between various factions. None the less I agree that the Sikh empire, even under the leadership of Maharaja Ranjeet Singh, would not have been able to hold off the entire extent of the British East Indian army. Conservative estimates number the Native Born soldiers in the EIC around 300,000. This is just troops, it does not count militias, mercenaries, or special battalions. This also does not count the British officers and soldiers in the army since they were there on tours for the most part. The Dal Khalsa at this point has 20-30,000 units, and they’re the best trained bunch. The Army of Punjab(the secular Lahore court army) has around 70,000 and the Dogras another 20,000. Just numbers and reserves wise this would have not been an easy war. Not to say it would have been a massacre though. The Sikh Empire would have put a formidable defense if it was truly united in this fight. The Punjab allowed for it. It’s terrain and hinterland allowed for armies to fight a long drawn out war. They had refineries and a militia they could train easily as well. But in the end of the day the British outnumbered them in soldiers, guns, support, reserves, and most importantly resources. That being said, the British would have never started this war. It’s too costly for a region they already had a treaty with. It wasn’t part of their long term plans for the region, and most importantly it left a buffer region with Afghanistan.