Honestly, even if literacy is not a problem it's really hard to see him getting a coaching job in the US. Henry was already in the US as a permanent resident.It's a huge difference and he didn't exactly hit the mother lode in terms of earnings. Remember that when he wanted to go back to Kenya he was so poor that people started a Go Fund Me for him. Ngugi would need a work visa and if I understand the process that means the AD looking to hire him would need to demonstrate that there is no US citizen or resident who can do the job. I think that's a really long shot if you're talking about coaching cross country or track.
And so much of coaching at a university involves more than training and race strategies. If he has some basic literacy problems is he going to be able to understand the NCAA manual fully? Will he be able to stay on top of all the paperwork that will come with the job? Is there a reason to believe he'll be able to recruit well? Does he have a history of coaching? If he's almost broke is he going to be able to afford a plane ticket to get here? How about rent, first month, last month, security deposit?
There's no harm in trying and I wish you and him luck here but I see so many obstacles here that if this is his only plan he's in trouble.