I found the answer already because I needed the answer fast. It is not possible. Also validated in the lab that there is no workaround to do it.
It is an expected behavior using ADMT tool in intra-forest migration where during migration of user object is deleted form the source domain and moved to the target domain. You can use Quest tool for migration which provide feature to rollback feature like keep object disabled during intraforest migration but its a paid tool.
http://awinish.wordpress.com/2011/10/04/quest-and-admt-comparison/
http://awinish.wordpress.com/2010/12/24/intraforest-interforest-migration/
ADMT 'moves' accounts and groups rather than 'copies' them https://social.technet.microsoft.com/Forums/en-US/8535c063-3711-4bad-b20e-f104f3e7357b/admt-intra-forest-migration-questions
ADMT 3.2 deletes source account after migration https://social.technet.microsoft.com/Forums/windowsserver/en-US/91d2b2eb-03eb-4399-979e-8df170e7b181/admt-32-deletes-source-account-after-migration?forum=winserverMigration