He was/is and even if he gets the 4/$100M he's supposedly seeking, should still be a neutral asset at least. Three and D, secondary creators can't not be and they especially are on teams who have players with unique ball skills at non traditional initiator positions and/or prefer to not have a heliocentric offense.
He could have been an starter while whatever PG of the future they ultimately draft develops and if they have positional size (a safe bet), he could play some alongside them and Vassell.
No, he doesn't provide rim pressure or plus playmaking, but good luck checking every box.
The Spurs do have a major talent issue. They're literally an unprecedently bad offensive team. They don't need to "blow their load" on an "all-in" move, but they do need some quality young veterans so that replacement players like Sochan and Branham aren't gifted starting jobs.
They need bridge players, even if they end up not being a part of the theoretical contention window or getting over the hump. I've said it ad nauseam, but Harris, Barton and Morris all had a hand in helping make the Nuggets contenders, but were turned into Gordon and Caldwell-Pope, who they needed to get over the hump.