I confess to a personal bias against these sorts of things.
I'm not going to be popular--peopel are going to jump all over me.
I think the surprise makes it all about the surpriser, and not at all about the surprisee. It's essentially selfish.
I also think it robs the surprisee of ANTICIPATION!
And personally, I really like anticipation. I like being able to say all week long, "my new boyfriend is taking me to the zoo!"
(My boyfriend was really into the surprise, and I had to break him of it, because it made MY life much less rich. If he hadn't understood my objections, I probably wouldn't have married him. He still likes surprising me, but he doesn't do it as often, because I object to missing out on all the "looking forward to it.")
(that's why I think these sorts of surprises are essentially a selfish act--HE gets the anticipation, but THEY don't)
Think how many more hours your family will have that are full of joy because they are looking forward to the arrival of their child. It won't diminish the excitement of seeing him for the first time. In my case, it would probably heighten it.
Even knowing that he might be able to come, and he's trying, would provide a level of joy (and confirmation of his love), even if it all fell through.
So I vote no, for those reasons.
And I'll also confess--the "soldier surprising his family" is just not new anymore. It's become a cliché. I was watching a video of such a surprise that was done at a football game, and I thought, I'd have been mildly annoyed.