You would be great in PR. 7 vs 5 % of total sales is not enough difference to make this articles point make any sense. It sold horribly on both platforms.
You may not be familliar with maths because selling 40% more despite having a service that canibalized most of the sales is a good thing( when I say most of the sales it is because 78% of games downloaded were on ps+), so it does makes sense to release a dlc where 83% of the people that downloaded the game are....Way more than where 5% are.
It is not PR it is pure logic...I will help you visualize it better, let's say the game sold a total of 1 000 000 (it is simply to help the math)...Then without counting ps+ the game sold 70 000 on ps and 50 000 on xbox that is a substantial heads up of 40% but then with the release of a dlc you are talking to the whole number of people that possess the game....That's 830 000 vs 50 000....Maybe one platform is worth devloping the dlc for and the other not so much....
That is without talking about funding if MS had accepted (I totally understand why they haven't but let's imagine)and had funded its coming to gamepass let's say exactly like they did with Haven so founding a fourth of the game...Then the devs would have no give any second thoughts and ported the dlc without any problems, because financially it's like their sales skyrocketed (funding would've garantedd at least a 25% of total expenses even without selling 1 game anywhere.
Edit: I made a slight mistake since I used xbox sales instead of ps sales ....So 85% and 850 000 vs 50 000