I hate to agree but they are right. Endpoint-spoofing and relaying between two spoofed endpoinbts is just one of the possible forms of mitm attack that just happens to be required if you happen need to open and re-pack encryption in order to evesdrop, or if you need to modify the data.

Spoofing the two endpoints to decrypt and re-encrypt, just so that you can evesdrop without modifying the data (other than the encryption) is certainly still "mitm". Yet all the man in the middle did was evesdrop. Becoming two endpoints in the middle was only an implimentetion detail required because of the encryption.

If you are admin of one of the mail servers along the way between sender and recipient and and can read all the plain smtp messages that pass through your hands like postcards without having to decrypt or spoof endpoints, that is still mitm.

So listening to wifi is no less. There is nothing substantive that makes it any different.

For endpoint-spoofing to be required for mitm, you would have to say that mitm only applies to modifying the data, which I don't think is so. Several purely evesdropping applications are still called mitm.

> for example, an attacker within range of an Wi-Fi access point hosting a network without encryption

The monkey in the middle doesn't get to "relay" anything either, but he can sure see it going over his head.