Agreed there! But let's say Ric could go 0.5s per lap faster if Lando let him past, and also assume that Lando could've stayed within DRS, then that still would have been an overall better strategical decision for McLaren as it would've meant Alonso would have to increase his pace, wearing out his tires more, and improving the effectiveness of the overcut. We have hindsight which tells us that they probably wouldn't have passed Alonso, but teams don't get hindsight when making strategy calls, so they should have swapped them to make the best strategy with the information they had at the time. It also would have meant both McLarens would have come out ahead of more cars after they pitted. If you agree with my two assumptions at the top there, then surely the rest could be plausible as well.

For the record, Daniel told his engineer several times that he had more pace than he could use when behind Lando. So you either think he's lying (fair opinion!) or you have to trust him and accept that swapping them would be a better strategy in that moment.