In the Texas guidelines it is worded slightly differently, i.e. " ...the Texas Master Gardener title is to be used only when doing unpaid volunteer work in this program." That's from:
http://mastergardener.tamu.edu...
Probably most of the MG rules are similar, the Mississippi MG's one is slightly different:
"“Master Gardener” is a nationally recognized title, but it has no service or
trademark status. However, the title “Mississippi Master Gardener” or
“Mississippi State University Extension Service Master Gardener” is used by
Extension to indicate a person who has been trained and certified through our
Extension program. Mississippi Master Gardeners are expected to use their title
only when doing unpaid volunteer educational work for Extension."
An MG can be "fired" for not following guidelines, but I don't know if use of the title in a way that the MG group considers inappropriate is significant enough grounds for such. I just remember reading these restrictions a while back. Perhaps it has to do with liability issues?
Limiting questions to MG's doesn't seem right to me either, I agree with Dave and Elaine. Would that mean that someone with a higher qualification in horticulture/botany/whatever would be excluded?