As I read this provision, it doesn’t say that aliens may vote for federal office holders. It merely provides the conditions under which aliens may vote for state office holders in “elections” where federal offices are also being voted. The enactors most certainly did intend to allow illegals or resident aliens to vote in federal elections.
I invite you to read it again. Section (c ) states that section (a) DOES NOT APPLY if...
So, this means there is no (a) if the voter is an alien who meets all three conditions in (c ). [Note: extra space added to avoid replacement with copyright symbol]
Ergo, under very limited conditions, an alien may vote for federal office candidates.
So, you are, practically speaking correct, but technically incorrect.
In a more normal world, say in 1987, I would not have a huge problem with the child of citizens voting, but one would want to ask why that child had not already become a citizen? That would render this whole law certainly less consequential or negligible in affecting any election outcome.
And I confess I do not know the naturalization laws.