Perhaps it's based on the definition of "healed"?
The number of hours/days/weeks/months without symptoms before a player should be cleared to return to play?
Some players never heal mentally. Their psyche is always conscious of the next big hit; that play which will start things all over again. That alone can ruin players, especially the finesse types. You think a guy was hesitant to go through traffic before? Wait until after a concussion. This sort of thing has ruined many players. Krys Kolanos being a great example. He was given all the time in the world to heal but just was never the same.
The article is also misleading. A 2nd or 3rd concussion is more damaging than the first. While you aren't any more 'likely' to get a concussion, the consequences of getting one will be worse. It's like saying you got a concussion by playing hockey so by quitting hockey you will be less likely to get another concussion. We'll file that one under the 'no ****' section.