Yes, it is. Any of the spies possible uses can be done by another class or a class partnered with another. I don't use the Steam forums because the users are incredibly hostile and only really care about getting kills. As evidence, remember when the Chargin' Tard/ Eyelander duo came out? Most people enjoyed it, not because it was in-character with the demoman, or it was a good weapon to use, but because it did 65 damage per hit and you were nearly invincible. They care about kills, not common sense.
And, if he meant that, it'd be more clever to say "This thread doesn't need you!"