Just something to consider:
Mesquite is a native tree...very drought hardy. On many farms and ranches is considered a weed! However, the pioneers used the ground-up seed pods for flour. I’m even seeing ground mesquite powder for sale in our local health food stores up here (not in mesquite country) for about $8.00/lb. My dad used the wood exclusively for cooking/smokiing wood. It has a WONDERFUL flavor!
Depending on the size of their property, if they have one (or several) already, they might want to consider keeping it/them. They are not very pretty and have thorns, so if they start taking over, they create a terrible environment for tires and should be thinned! But they could be a source of nutrition as well as warmth in a pinch.
I was all set to run out and get some until you got to the part about thorns. Other than rosa rugosa, I try to avoid thorns and go for the thornless varieties of berries whenever possible.
The mesquite beans make a wonderful jelly too, just don’t keep the jelly, even sealed, over 10 months, it turns black, as does the honey. I agree TEXOKIE, mesquite has a wonderful flavor for cooking. Mac & cheese are improved when baked in a pit using mesquite.