Final Settlement - LTA should be availed during the service tenure of the employee and cannot be claimed after resignation?

In the topic payment of LTA At The Time Of Final Settlement, can a company have the following remarks in their appointment/agreement letter :
LTA should be availed during the service tenure of the employee and cannot be claimed after resignation.
or
Can a company exclude LTA from CTC. By doing this can they deny paying LTA for resigned employees

Most of the organisations have this clause that LTA/LTC is allowed to the employee while in service and the resigned employee cannot avail it. This is so in Govt/PSU sector. In deed allowing LTA to a resigned employee is counter productive as the organisation would need the continuous services of the resigned employee for the notice period for ensuring continuity and smooth take over purposes.
LTA is a cost incurred to the organisation and hence would be a part of the CTC. Denial of LTA to resigned employee is not linked to its inclusion or exclusion from CTC. As a matter of fact CTC is a notional calculation based on employee entitlements and an actuarial value is added for certain benefits, but it would not mean that the employee would get all that money.