SERVER-88750 added an experimental bypassEmptyTsReplacement flag that tells the server to accept Timestamp(0, 0) as a literal rather than replacing it with current time. This is needed to solve certain data consistency problems in both mongosync and mongorestore. (See CA-34 for details.)

mongorestore uses the driver's BulkWrite interface. As best I can tell that interface offers no way to pass bypassEmptyTsReplacement to the server; thus, we can't actually fix the consistency problem without help from the driver.

I suspect this would most sensibly be implemented as a generic means of passing custom parameters to the underlying insert, replace, etc.