i don't know enough about meniscus but apparently it can be healed without surgery depending on seriousness
Luckily I do know about it.
That is accurate. Throw a rock on the street you might hit someone with a torn meniscus and they never knew they had it.
Symptomatic pro athlete? Most will get it fixed because it WILL flare up again with training.
You go in with a camera, find the tear and shave it out into a smooth edge.
Recovery time for the average joe? 3-4 weeks. Pro athlete faster. On some less than legal substances? even faster.
That's faster than any sort of rehab he is planning.
Story doesn't add up IF he had a torn meniscus AND he had pain from it while training AND he wants to be a pro fighter.