How about (Build.VERSION.SDK_INT < Build.VERSION_CODES.KITKAT) || (Telephony.Sms.GetDefaultSmsPackage(context) == context.getPackageName()).  That way you can just call isDefaultSmsProvider() and it will return true for < kitkat or if >= kitkat and registered as the default.

You can then get rid of the whole shouldNotify variable below and just do putExtra("should_notify", isDefaultSmsProvider()).