So Macropodus - has your original question been answered? It seems like your question is more related to how Morph Market works rather than this specific animal.
No "trait" was listed and sellers are apparently not required to list one. If there was a 'dinker' trait to select, I'm sure that's how this snake would have been labeled.
"Dinker" has been a relatively recent addition to the MorphMarket options for searchable traits. It's quite possible that this listing was created before that option was available, or that the seller simply chose not to use it. Either way...