After 14 days, most nodes would have dropped the transaction from their mempool and the sender will be able to rebroadcast the transaction again, but which can be to another address if he wants.

Mempool has not be less congested lately to the extent that transaction of 10 sat/vbyte are getting confirmed. The least seen recently is 14 sat/vbyte.

You can wait because maybe the mempool can become less congested, but the probability that the transaction will be confirmed is very low.

Do not accept the transaction until it is confirmed. And always tell him to pump the fee.