I don't Think the contractor can assign anything after the contract period - the job is supposed to complete within the contract period - so there is nothing more to assign after that. During DLP only repairs are to be done- not new works.
Most of the time for D&B projects, the deed of assignment is done in the "Dasar Pengagihan Kerja Kepada Kontraktor Bumiputera" - to get their payment directly from the government & not from the main contractor - to ensure the that payment is received for work done.
Basically it is also stated in clause 40 that if the main contractor's contract is terminated - then automatically the sub-contractor's contract is also terminated.
Maybe our experienced QS can give a better explaination.