465 has always had priority and continuity in exit numbering and mileposting, similar to how I-83 hops on and off of 695 in Baltimore, but of course this is a much longer overlap, even carrying through the zero-point of 465.
As far as the Columbus sign, it is sensible inside 465 for I-70 EB to start showing the control city to the east, as 70 approaches the I-65 overlap/mixing bowl area and having the control cities makes it easier to follow your intended route as you approach. You see Louisville, Columbus, and Chicago (the latter two on the same sign for the duplex) as you approach the southern split from the west, and then Chicago and Columbus separately at the north split when the routes split. Signing I-70 for Columbus gives people an additional anchor for navigating the successive splits, especially if you are unfamiliar with the area. ("Okay, I want 70 eastbound, keep following the signs for Columbus.")
Of course, Columbus has been disappearing over the last decade in favor of Dayton. Old signs often said "Columbus OH" to avoid confusion with Columbus, Indiana which is south of Indy on 65. One sign on I-65 SB coming into Indy for I-70 EB says "Columbus O." in the old idiom, in button copy to boot. Long may it live.
One other interesting thing about the pics is that the signs there were apparently among the last to be installed with lighting in the area, although all the lighted signs in town appear to no longer have the lights turned on. The most recent overhead installs in that area don't have the lighting fixtures at all, as seen upthread with the Exit 16 signs with tape-overs still hiding stuff yet to be opened.