Wow — you’re reading a great deal into that tweet, aren’t you?
First: You don’t know that these were “massive” donations. The tweet doesn’t say how much each of these “private” people donated.
Second: You don’t know that these people met with Hillary Clinton in her “official capacity” as Secretary of State. They could have met with her due to her association with the Clinton Foundation. The tweet doesn’t say.
Third: You don’t know that any of these meetings were improper in any way. The tweet doesn’t say.
The tweet was obviously meant to be provocative and imply things unsaid. And it worked — with you.