Mr. Dill & I are on the same side as this one.  Every human endeavor has
limits & limitations.  One of the reasons, among many, that I don't dye my
hair purple, green and pink stripes is that my colleagues both paid and
unpaid would likely loose confidence in me.  I would have limited
confidence in a volunteer who collects in competition with my employer (as
defined by Mr. Dill).  It may be harsh but the bottom line is if a
volunteer can't be trusted to not harm the institution what good are they.
 And if they do not wish to change their practices or disclose their
activities, maybe they need to volunteer at the homeless shelter or the
literacy center.  We don't have to take all offers even if they are free,
especially if there is a potential for more harm than good.