That is a good question. I couldn't find a citation for the original comment, but my guess would be either that they want an unbiased cohort OR, since its a bacterial treatment, they wouldn't want to risk the spread and possibly contaminating children after the trial was done.

Maybe some attempt to prevent a contagion that would rapidly spread to many households through the children?

Because of ethanol?

Maybe. You could possibly now fall foul of certain alcohol production laws....