So thanks to @mcowger, here is the answer. The deletion of the TTF files can be turned off in the adapter configuration:

In the following file (on the analytics VM):

/usr/lib/vmware-vcops/user/plugins/inbound/emc_symmetrix_adapter3/conf/emc_symmetrix.properties

Change this option to 'TRUE':

BACKUP_COMPRESSED_INPUT_FILES_AFTER_PROCESSING=false

And restart vCops.