This is only half of the story, as the July schedule increase is not yet loaded. UA has been saying its capacity distribution will be much more seasonal going forward, so I don't see anything new here.
What increase? they're cutting in the winter, not increasing in the summer. You might have a couple marginal aircraft that won't be in for MX than would otherwise be, but otherwise, they already run an excessively tight schedule and won't be adding more capacity.