Given no further context, when I hear "portable battery" I think of a battery that is portable in itself. An iPhone is portable, but the battery embedded in it isn't. Contrast the battery pack that something like an ICOM walkie talkie would have, which is portable in itself.
Other ways to see it: An Electron program is portable, a .exe program is not portable; they are both programs. A stick of RAM is portable, soldered RAM on a motherboard or in a CPU is not portable; they are both RAM.
The comment I replied to mentioned "portable batteries" will be required to be "removable/replaceable", which sounds like an oxymoron because the entire point of a portable battery is that it's removable/replaceable.
The proper understanding was that electronics ("appliances") will become required to have portable batteries, because most batteries in them today are not portable.
If I'm still not coming across, let me put it this way: "Portable" in "portable iPhone" is a modifier on "iPhone", it is irrelevant with regards to the iPhone's battery which as of today is decidedly not portable anyway.
If I'm still not coming across: An iPhone being portable does not mean its battery is also portable.
You're coming across just fine. The problem is that you made a sweeping generalization that "I think we can all agree" when it is obvious that we cannot. Your definition does not make sense to me, just as mine does not make sense to you. Neither one matters anyway now that there is a legal definition that must be adhered to.
Other ways to see it: An Electron program is portable, a .exe program is not portable; they are both programs. A stick of RAM is portable, soldered RAM on a motherboard or in a CPU is not portable; they are both RAM.