As above, doesn't stop vandalism or removal of the parts, looks like much more of a faff at either end to rebuild the bike before you can ride off on it, people are quite set about saddle height & the idea of someone having to put a scale or clear, weather and scuff proof marking onto the stem just to get it in the same place every single time....., it appears not quite as unstealable as the headline trumpets & the lad tacitly admits this in the article. It is introducing an element of structural weakness/more moving parts to wear &/or go wrong into the very bit of the bike you need rigid, solid and reliable; and a piece that is usually not prone to such aspects of wear and tear; adding further to the long term expense of owning such a bike.
You'd also potentially need to be making even more of a faff removing the wheels to fit into the already bulky locked up lump or carrying additional cable/locks anyway to make them as secure as a decent lock does already with barely any interaction with them.
Even if your average scrote can't be bothered to kick the spokes in, a quick squirt of superglue in the lock and you've wrecked an entire bike not just a cable or U lock that can be cut away and replaced far more cheaply.
