In traditional songs things don't really have to work logically
- for example, in this song, there's the lyric, "She's as tall
as any pine, And as straight as a pumpkin vine." So the last
verse of the song goes,
"How old may she be,
Billy Boy, Billy Boy?
How old may she be,
Charming Billy?
Three times six and four times seven,
Twenty eight and eleven,
She's a young thing,
And cannot leave her mother."
This, despite the questionable math, puts the refrain
into a very ironic context.
My understanding of square dance singing calls is that
many of them were set to popular music of the time (though I
have no idea about this particular one). So if your audience
was expected to know this song and the context behind the
refrain, that would be one thing. Notably,
though, the square dance-edited version is missing this
context, and it adds the line "Promenade
this pretty thing, won't you help me to sing" to the
refrain, "She's a young thing, And cannot leave her
mother"! So it'd be quite something else to hear
this line on its own, which makes it sound like you should
be promenading with your underage partners/corners.
There's no universal answer to "is this acceptable"
because it depends on your "contra dance crowd" who is doing
the accepting - this can vary widely between dances, even
within the same city. You'll have to figure out if the
dancers are ok with it as is, might be ok with it if you
give them some background about the song before you do the
walkthrough, or would not be ok even with that. However, I
think you'll find a lot of other material is less
objectionable to any audience (and you already have some
intuition for this, since you asked the callers list about
this one).