I don't believe "prophesies" in the sense that Paul was writing about it in
1 Cor. 14 has anything to do with "future" events, or foretelling. Paul says in
1 Cor. 14:3 "But he that prophesieth speath unto men to edification, and exhortation, and comfort."
There are three criteria here to prophesying:
1. Edification.
2. Exhortation.
3. Comfort.
There is nothing here about foretelling future events.
So, first of all, under the above criteria outlined by the Apostle Paul, I would not consider what that missionary said as "prophesy". Now, if he had said, God wants to encourage this congregation to reach out to sinners who have not yet come into the fold... or something of that nature... (just an example) that to me, would be more in keeping with prophesying, because it is edifying, exhorting, and comforting the body of Christ, all in the same time, without foretelling a future event.
Now, if you look at the gift of the word of knowledge... that may be more in keeping with the words spoken by the man you quoted. Of course, all words of knowledge are subject to scrutiny for their truthfulness. Only God could foreknow if such an event were to take place, and if it doesn't, then the word of knowledge was false.
I Cor. 12:8 "For to one is given by the Spirit the word of wisdom; to another the word of knowledge by the same Spirit."
Just my thoughts...