It seems like an odd choice at the very end of spring ball. They're done after Saturday, right? If I'm anyone but a QB I'd want it to be live tackling, and they always green jersey the QBs regardless.
I would get it more if they were having an open scrimmage with games sometime in the near future, try not to bang guys up ahead of all that. It's not like dudes can't get injured if you're not tackling to the ground. Fidone we know was a non-contact injury. Dunno about Honas.
Honestly the theory that makes the most sense was to keep their headhunting safeties from getting all hyped in front of the crowd and concussing reserve WRs when some backup hangs them up late over the middle.