"Singular" is intrinsically an integer measure. 1.0 doesn't qualify as an integer, so the plural is appropriate.

Dictionary.com says this:

Grammar . noting or pertaining to a member of the category of
number found in many languages that indicates that a word form
has one referent or denotes one person, place, thing, or instance,...

1.0 does not refer to a single thing, it is a dimensional measure of size. It doesn't qualify as singular.

"Singular" is intrinsically an integer measure. 1.0 doesn't qualify as an integer, so the plural is appropriate.

Dictionary.com says this:

Grammar . noting or pertaining to a member of the category of
number found in many languages that indicates that a word form
has one referent or denotes one person, place, thing, or instance,...

1.0 does not refer to a single thing, it is a dimensional measure of size. It doesn't qualify as singular.