But, it just doesn't
It says that the attacker kicking it into the defender's arm from close by, when the arm is in unnatural position, should be a DFK.
It doesn't say anything about teammates kicking it into the arm, nor about unexpected deflections or plays of the ball that are not kicks (which is a defined term, and does not include playing the ball with the shin or knee or higher) nor about,
well, anything at all that is not an attacker kicking the ball into the defender's unnatural-position arm...
Defender AA has lunged and makes a legitimate tackle, and ends up on their hands and knees with the ball nearby.
AA sees Defender BB about to kick it into their arm, so AA lifts their arms off the ground out of the way, making their silhouette larger but removing any direct obstacle from the ball's path. BB scuffs the kick, which bounces off AA's knee and into their raised arm.
The IFAB tweet has nothing to do with this situation, since it hasn't got an attacker involved and the ball is coming via a deflection off their own body, so we can go purely off the law text. There's been no effect worth mentioning on the attacking team here, and the defenders are in no different a position than they would be if AA had not been there when BB kicked it. We've already had one example of a high level referee call this fine, play on, in this very thread.
So, would you call this a handball offence under the laws as written? And if not, why would the tweet change that, when the only matching detail is that the ball hit someone's arm?