HARD disagree here.

Yes, they aren't in use most of the time, but they don't necessarily create any problems with Walkability.

Ravens stadium and Orioles park are both close to downtown, and they don't affect walkability in the slightest.

RFK used to be near the Heart of DC and didnt affect walkability at all. Nats Park doesn't affect walkability. Neither does Cap1

Its a non-issue, unless the planning team is crazy incompetent.

And for the times that it IS in use, that's not just a sports venue, but an event/concert venue that is easily accessible by foot or public transit.