The feature is probably named after Captain Thomas Johnson, Master of the British brigMellona or Captain Robert Johnson, Master of the American sealing ship Jane Maria and of the schooner Wasp, who visited the South Shetland Islands in the first seasons after their discovery.
Isla Livingston: Península Hurd. Mapa topográfico de escala 1:25000. Madrid: Servicio Geográfico del Ejército, 1991. (Map reproduced on p. 16 of the linked work)
Antarctic Digital Database (ADD). Scale 1:250000 topographic map of Antarctica. Scientific Committee on Antarctic Research (SCAR). Since 1993, regularly upgraded and updated.