Raise the valleys

I was recently contacted by a בעל דקדוק whom I trust regarding a פסוק in this week's הפטרה:

כָּל גֶּיא יִנָּשֵׂא

Since the word גֶּיא does not have any vowel under the יו"ד, the letter is completely silent and therefore, should be pronounced with a סגול and should not sound like a צירי. And this is how he instructed the Bar Mitzvah boy he was teaching to pronounce it. (Most other times you see this word it is סמוך and there is therefore a צירי under the יו"ד.)