In many situation i was needed to exclude specific computers (mostly servers), from getting SCCM client to be installed after configuring site-wide automatic client push installation method.
There is an option for editing the registry and add ExcludeServers list with all computers names that SCCM client shouldn't be install.
Basically, adding the ExcludeServers list with computer names will sets the install flag for that resource which prevent from the client to be installed automatically.