He cannot possibly be saying that, since Paul already said: Have all the gifts of healing? do all speak with tongues? do all interpret? Which means "all DO NOT speak with tongues".
While it's true that not all do speak in tongues, that does not change the meaning of verse 5: "Now I want you all to speak in tongues".
And remember, the overall context is in meetings. In meetings, not everyone does prophesy, speak in tongues and interpret, etc.
Well the Bible refutes that quite easily, since manifestations = gifts.
That's not true. Check any dictionary.
Now concerning spiritual gifts, brethren, I would not have you ignorant...
Note that the word "gifts" is in italics. It was added. The word is "pneumatikos", and it means spiritual things, or spiritual matters.
Now there are diversities of gifts, but the same Spirit...
That's right, there are diversities of gifts. But what does verse 7 say?
1 Cor 12:
7) But the manifestation of the Spirit is given to every man to profit withal.
There are diversities of gifts, differences of administrations, diversities of operations, but the manifestation of the spirit is given to EVERY man (Christian).
To another the working of miracles; to another prophecy; to another discerning of spirits; to another divers kinds of tongues; to another the interpretation of tongues:
Again, the overall context is meetings. Different people do different things. If each person could operate only one manifestation, then Paul contradicts himself in 1 Cor 14, where he says the person who speaks in tongues is to be the one to interpret. And he is also to covet to prophesy.