e.g. the L3f2 and L3e5 sub-clades that seem to be autochthonous to the Chad Basin."
Lets not kid ourselves, they want an excuse to refuse applications for asylum, this will give them another excuse.
They want to tackle asylum seekers because there was a backlash against immigration, after UK became swamped with immigrants. The immigration that swamped the UK came from Eastern Europe, and Blair campaigned for the rapid (IMHO too rapid) EU expansion into the east. So they were partly to blame and could not fix that.
So they talked up 'illegal' immigrants instead, hence stopping a hundred Africans is the fix because they couldn't do anything about the millions of Eastern Europe immigrants legally entering the country.
Even if it means pseudo science and crazy eugenics stuff they want to keep secret. So they'll see L3f2 and say "no, you must be from Chad" and they know it means squat, but it is the excuse for refusal needed to defeat their duty under the UN Convention on Refugees.
It doesn't fix immigration, because it doesn't apply to EU citizens, it doesn't work, or have a useful purpose or is cost effective, but that doesn't matter. It is a sop to the BNP voters and for that purpose it works.