Silversand - Medical Air Services Inc don't sell evac insurance, they only arrange logistics with carriers. Unless you pay out of pocket, it's up to the insurance plan who they will hire for evac.
I've looked into evac plans both as a part of insurance and standalone evac's from $50/year to $400/year, they mostly vary in where they take you to. Vast majority - especially those included in medical insurance - will take you to the "nearest suitable hospital" which would be $$$ US or CIMA (the latter is not for "poor Mexico", they charge almost like a US hospital). $400/year standalone evac will take you to the city specified in a contract, but this is only evac, treatment not included.
I wonder whether any private hospital in Baja or Baja Sur even has Regen-Cov on hand.
Another thing with evac plan - you can't ask to be flown to the US where they will give you Regen-Cov infusion when you have no symptoms but tested positive, or to Canada where they give Regen-Cov when you are tested positive and have at least mild symptoms (Canadian system is greedier). Nope. You must be hospitalized to be eligible for evac - can be a cot in a shack, anything, as long as there is a Doc to certify your condition. In plans where evac is a part of medical insurance, it is the same - you must be in danger to lose your life or an organ if not treated within 24 hours (if memory doesn't fail me).