If it's true that most of these new entries to the ODO are obsolete words that have no recorded usage examples in recent history, then I think they'll have to do something about it. Obscure words and regional dialect words have always been in the dictionary, and allowed on Countdown, but those words have been in current usage. If they really have imported the whole OED into ODO, then most of the new entries will be words that nobody has used for hundreds of years, and it would seem silly to allow them in a word game.
However, I don't think that's happened. What makes you think the whole of the OED, or most of it, has gone into ODO? I've just taken a random volume from
my copy of the 20-volume OED (it happens to be volume 6), picked some words at random from that, and looked up the ones I didn't know on ODO. The uncommon words I found in the OED were GLYCURONIC (a chemistry term referring to glucuronic acid), GLYDE (a variant of GLEYD, an old horse), GUBBLE ("to make the sound rendered by 'gub': a verb formed to imitate an inarticulate sound"), FORHARDEN (the same as FORHARD, which means "to harden"), GENTY (genteel), GARGARIZE (to gargle), GRAMOCHE (a variant of GRAMASH, which in turn is a variant of
GAMASH), and FULVOUS (dull yellowish-brown or tawny). Of those OED words, the only ones in the ODO are FULVOUS and GAMASH (though not GRAMOCHE or GRAMASH), and FULVOUS seems to have been in for a while anyway.
In the interest of full disclosure, I also randomly landed on GRAVITATE, GALLERY, FORGOTTEN, GUMBOIL and GLARE, but didn't bother looking them up on ODO because they're reasonably well-known.
So are we sure these new entries are just historical? Perhaps "gointer" and "gwine" are in current usage but we just haven't heard them. Just because a word is marked "rare" and we haven't heard of it, doesn't mean it shouldn't be allowed as long it can reasonably be described as being part of modern English. For example, we all expect DELATION to be allowed even though it's "archaic".