Your original implementation is sub-optimal - you can just sum true values:
return (int)a + (int)b + (int)c >= 2;
Obviously you can extend this to 10 variables:
return (int)a + (int)b + (int)c + (int)d + (int)e +
(int)f + (int)g + (int)h + (int)i + (int)j >= 2;