In any case, he'll have at least six starts between now and the end of the season: the Memorial next week, the Quicken Loans National, then four sponsor exemptions. He could still play his way into the U.S. Open via sectional qualifying, or the Open Championship via finishing in the top four among non-exempt players at one of the PGA or Euro Tour events designated as an Open qualifier.
If I was advising him, I'd tell him to take two weeks off if he doesn't make it into the U.S. Open field, then bank as many of his sponsor exemptions as he can until after the Open Championship, when the compressed schedule starts having an effect on the top players. In fact, he should probably try to get into the field at either the French or Scottish Open for a second attempt at Open qualifying rather than use one of his exemptions to play St. Jude (which would be his fourth tournament in four weeks) or Greenbrier (has only one qualifying slot instead of four).
His schedule from here on out should be: Memorial, U.S. Open (if he qualifies), Quicken Loans National, either the French or Scottish Open, the Open Championship (if he qualifies) or Barbasol Championship (if he doesn't), the Canadian Open, and two out of three between the Travelers Championship, John Deere Classic, and Wyndham Championship (or all three if he qualifies for the Open Champuonship). That's my opinion, at least.
Welcome to the site @Swungover! You'll be pleased to know there are quite a few good courses in your area. The Mercer County Parks system does a really good job for it's residents. The Mercer Oaks East and West Courses as well as Mountain View are some challenging tracks. Just don't push that shoulder too hard.
Rather than chair, let's be a bit more realistic and ask about a bench, like one adjacent to another tee box. If your ball were next to it, are you saying that you couldn't place a foot on that particular immovable obstruction, in taking your stance to play your next shot?