I see him as the change of pace. If Akers misses time and you have to hand the ball to Kyren 20+ times what happens. I'd rather not find out. Plus that backup has to be able to sustain over multiple games, which for next year is important to consider.
Basically there are two roles in an NFL backfield. McVay mixes them but that is only a good thing when you have a back who can do it all. Without that back then there are two separate roles those being the bell cow who eats the carries to keep the defense honest and the change of pace who is your typical third down type who can threaten more in the pattern or pass block well enough to be on the field.
Kyren is the latter. How long would he survive as the former? Again I don't want to find out. Preserve him by having a bell cow backup who can eat the carries.
For next season we will need either a backup to that bell cow function or a RB who is so good that he can do both. Either works. But for now why not add a guy we know can be a fine backup and rotation back as that bell cow.
