Any process that increases the rate, frequency, or extent of epithelial to mesenchymal transition. Epithelial to mesenchymal transition where a mesodermal cell loses apical/basolateral polarity, severs intercellular adhesive junctions, degrades basement membrane components and becomes a migratory mesenchymal cell as part of the process of gastrulation.
positive regulation of mesodermal to mesenchymal transition involved in gastrulation