Can you use the Twinned Spell Metamagic on Greater Invisibility?

Question

Jeremy Crawford clarified in the 19/JAN/2017 Sage Advice segment of the Dragon Talk podcast that a spell targets something if it affects that thing.

The Twinned Spell Metamagic states:

When you cast a spell that targets only one creature and doesn’t have a range of self... Emphasis mine

I am not sure how to interpret this section though. Does the spell need to target exactly one creature and nothing else, or can it target one creature and then also any number of non-creature things, such as objects? However, in the podcast Crawford does say fireball is not eligible to be twinned "Not only because initially you're not even targeting a creature, you're actually targeting a point in space...", and this seems to imply that my first interpretation is correct.

This matters because greater invisibility has the following in its spell description:

Anything the target is wearing or carrying is invisible...

The answers to this question about what counts as a target, seem to say that worn/carried objects are included when a spell targets a creature. Does this mean the additional sentence in greater invisibility is just a helpful reminder?

Answer 1

The Player's Handbook received errata that added a paragraph to Twinned Spell to clarify this wording (emphasis mine):

Twinned Spell (p. 102). A new paragraph appears at the end of this subsection: “To be eligible, a spell must be incapable of targeting more than one creature at the spell’s current level. For example, magic missile and scorching ray aren’t eligible, but ray of frost and chromatic orb are.”

Greater Invisibility can only target one creature, even when cast using higher level spell slots. Therefore, Twinned Spell can be used on Greater Invisibilty.

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The additional sentence in greater invisibility:

Anything the target is wearing or carrying is invisible as long as it is on the target’s person.

is only there to clarify what happens to things carried by the target if they drop them or doff them or if the things otherwise leave the target's person.