Over the years, I have very quietly proposed to Admin the award of quite a few Knowledgeable badges - ALL, save 1, have been accepted.
This sort of thing is best done out of the public's eye and with gentle persuasion from a Curator.
Knowledgeable does not mean perfect opinion, nor a useful stick for shifting Likely Banners.
It's my experience that those with Knowledgeable badges become cautiously VERY useful. My fourth Icons in Marine Plants and inverts is mostly courtesy of them.
If I may say, INcautiously, that in iSpot SA there might have been too may experts (did I write that?) The result was rapid rise to power (to four or five icons) of some whose experience was weak and whose power was overplayed (I think 5 icons have the same score-weight as Knowledgeable).
Here the opposite is possibly true. There are many, in the other two Communities, whose knowledge, commitment, excellence in posting and, don't forget the crucial, agreements-trail, is worthy of the Knowledgeable badge.
Personally, I do not think anyone should refuse a knowledgeable badge, if offered, on the grounds it should be seen as very valuable to the rank and file poster and for the future of iSpot.