It is generally some HR-driven BS written by people who have no clue about pilots competencies. In their mind if you have your last flight within the last 12 months you are a tip-top candidate who will encounter no issues during OCC/type ratings - not withstanding the fact that you maybe flying as a cowboy.
I have trained/checked several crew members coming back from long term sickness (2+ years) and nobody ever encountered any issue with the proposed return to line programs.
Provided a pilot maintains a good level of knowledge while being grounded, all the rest can be easily retrained.
Actually in some cases people became even better professionals than they used to be ; an extended ground time brought back the passion and the eagerness to go back in the air.