Why would someone as good as LF five 2 shits about competition? If he is the best he will play. Period.
And he probably will be.
Competition still matters.
When LF arrives on campus, will he know the playbook as well as the upperclassmen? Will he have the experience in recognizing SEC blitz packages? What if your QB gets knocked out because the freshman RB didn't block the right guy?
It's not enough for LF to just be the best runner. If he wants to start as a freshman, he probably needs to be a considerably better runner. What if he gets a minor, nagging injury that keeps him at 95% for a while, like an ankle sprain that limits his cutting ability? Is he still better?
If LF wants to start from Day 1, there are plenty of reasons for him to choose the less crowded backfield of LSU.