ESI Eligibility After 58 Years - Continuing In Service With All Benefits

We have one employee who has retired in 2016 and is continuing in service with all benefits such as PF, Bonus, Leave Encashment etc. His pay package include HRA, Medical Allowance, Conveyance and other allowances and is similar to all employees in the Pay roll.
His work location is in a hill station in Tamil Nadu and he is the care taker of company Guest House. His salary is processed in the Corporate office in Chennai. This area also not covered under ESI during his service period. Now this area is covered under ESI.
His present gross salary is below Rs.21000/-. Before retirement, he was not the member of ESI because he grossed the earlier ceiling of Rs.15,000/-.
My query is whether it is mandatory to deduct ESI from him and remit the contributions to ESI. In that case, we have to register in ESIC portal as a new IP.
I request seniors to give an opinion on the query.
Regards,

Sir, in my opinion, if the wages of the said employee posted in Guest House of Company are booked in the accounts of Company, then the employee (even though retired) is covered/coverable from the date the area is declared as implemented area under section 1(3) of ESI Act, 1948 or from the date the said employee is posted in the said implemented area, whichever is later. However, for more clarification and procedures, it will be more better if you contact the appropriate Branch Office of ESIC which is for the area of said "hill station" as mentioned by you. Though you can obtain Insurance Number of said employee by complying as per online procedure, but I feel that the appropriate Branch Office of ESIC is the concerned office which can guide more accurately in procedural matters.

ESIC has no bar for age factor, if the employee had ESIC membership in any time during his lifetime service then that card can get validated,
and yes the employer has to obtain a sub code for that specific location ( newly implemented area) .