Brandis said warrants should be "sufficiently strong to require companies, if need be, to assist in response to a warrant to assist law enforcement or intelligence to decrypt a communication". A company which makes end-to-end encryption will not be able to assist law enforcement in this way unless they make a backdoor.
Conclusion: Brandis either doesn't know what a backdoor is, or he does know but realises that "backdoor" has negative connotations so he is pretending that that's not what it is. Both possibilities are pretty reprehensible in my opinion.
