What variety of apple is it? Why won't it bloom? You're in San Diego zone 10? Do you get enough chilling hours for it to bloom? Loquat is a tropical tree and I don't think it's even in the rose family like apples and pears. You need to have similar species to graft onto. Apples are related to pears, quince, crabapples of course, mountain ash/ Rowan. I'd say make sure your apple variety is suitable for your area, make sure soil is right, care for properly, etc. make sure you have enough phosphorus in soil to promote bloom. Have soil test. I had to use super phosphate to get my crabapples and apples to bloom well because my soil test showed phosphorus deficiency.