The Whitehouse generals are so worried about an accidental nuclear war that Trump.com™ might start in a fit of blind rage and spite they have hired Kaepernick to tackle the president if he lunges for the nuke football.
They said he seemed a prefect fit for the role given his football experience and that Trump.com™ seemed to be a big fan of his, given how much he tweets about him. They also said he seemed to be out of a job so he was free and kneeling so much gave him a good players position to quickly sprint across the room to tackle Trump.com™.
Mattis and Kelly like the guy as they say not only his he deeply religious with his constant kneeling but is also a proven ball runner able to run 100 yards with a football better than most. This would get the football well out of Trump.com™ range until his latest nappy dummy spit abated.
When asked how will they disguise him so he can hide in a corner of oval office (finding a corner in an oval might be a small glitch in the plan), they were going to use a variation used by both Steve Martin in Inspector Cluzo and Robert Downey Jr. in Sherlock Holmes, Wallpaper Camouflage. The plan is he could lurk in the corner (when he finds one) watching for tiny tot tantrums then launch from his camouflage spot, tackle Trump.com™, grab the football and flee the Secret Service to an undisclosed location. Then when signaled by the generals return the football when there are some adults in the room.
When Kaepernick was asked what he thought of his new gig he ecstatically replied, "well its fantastic. I get to knell and pray a lot and save the world, by the looks of it nearly every week. It was great to put his learned skills to saving humanities future, instead of just being a rich white guys show pony. Now i get to tackle the rich white guy, tell me a better sport than that".