It is a boilerplate note they put on anytime the DME is not
frequency-paired with the ILS.

There are zillions of arcs to localizers that don't have this note.
The 8260.19C says they only apply to approaches with DME in the title.
I have an old plate for this approach, and it lacks the note.

But, you're right, you could easily fly the ARC, then use the lead
radials to change to the LOC.

That is precisely the purpose of the lead radials, is it not?