My best guess, "no extension" whatsoever. Your cousin's intentions were severely doubted by the POE officer. He/she could have easily denied him entry, but decided to grant 4 weeks of entry with the condition that your cousin is left no avenue to extended his stay in any form or shape. Your cousin needs to depart by Nov 18th. This will work in favour of him and next time he may get the default 6 month stay.