In my line of work I see the horrific consequences of drink driving more so than most, and for the record I do think drink-driving (along with many other offences) is inexcusable.
With that said, I don't think we can categorically say that, because this woman has done what she's done, she is inherently "bad" - and certainly can't say that she (and her innocent kids) need to be killed or removed from the gene pool, based on the information contained in what is basically a newspaper clip.
For all we know this woman may have been a hard working, and until this point, law abiding and careful mother, who for the first time in her life has made a monumental mistake, perhaps with underlying tragedy as a contributing factor, and will never do so again. In this case, the sentence is probably quite appropriate. We must remember that we only have what is printed in the paper, and don't have all the facts upon which the magistrates would have decided this case.
I don't like the comment either, but it may of course be that TB is joking, and that his comment is simply dark humour.