I'm having trouble reading some of the earlier responses in this thread, with black backgrounds and gray text font, so at the risk of repeating some responses, I'm going to offer the following...
Typically for Exadata sources, Delphix uses either one (or more) of the Exadata compute nodes as target servers, or else completely separate Linux x86-64 servers as target servers.
Regardless of what server is used for compute, Delphix VDBs can be provisioned to these target servers from Exadata sources, whether HCC is in use or not.
HCC is usable only on Oracle-branded storage (i.e. Exa, ZFSSA, Pillar), so HCC tables are unreadable within Delphix VDBs unless appropriate "ALTER TABLE ... MOVE ..." commands are configured to rebuild the HCC tables (usually as COMPRESS BASIC) using Delphix "configure clone" hooks.
As for HJ's original question, applying patches to the target VDB system should be considered very carefully. Exadata patches are often comprehensive bundled patches, so they may include changes for storage nodes, compute nodes, and database.
If you are testing a database-only patch, then no problems; the patch will affect only the Delphix VDB.
If the patch is more comprehensive and bundled, and hits more than just database, then please exercise caution. Delphix can virtualize binaries and other file-systems as well as databases, allowing testing of patches to the RDBMS binaries, but comprehensive Exadata bundle patches might go beyond that and update the OS or firmware on the compute node, which Delphix can not and does not virtualize.
Hope this helps...