I suppose it’s a slightly more accurate term. The messages here are not truly private since they are not encrypted, but since they are sent directly no one should read them in the normal course of using the platform. Calling them private might imply to people that other people cannot read them, rather than the reality that it is just very unlikely anyone will. I would also argue that if something is released to an authority it is not “private” even if it is not publicly available.
Honestly, it doesn’t really matter which you use. People will generally understand either way, so you can go ahead and keep saying PM and others will say DM and we can all just understand that they mean the same thing.
I get that the EFF has to say this bill has “laudable goals” for political reasons, but that couldn’t be further from the truth. Protecting children is a typical excuse for broad expansion of State power, and this is no different. Don’t be fooled, and remember it’s the democrats who are trying to push this through. Both major political parties in the US are enemies to personal autonomy, one is just more subtle about it. Liberation will never come from within the ruling power structure.