Yup, This is just a stunt. RF emitted from electronic components has been hacked ever since the days of the TV license vans.
They alway fails on loads of points. . 1/ more than one computer in use screws up the output. 2/ A faraday cage, or a tempested PC emits no RF. 3/ you need to be close.
Its such a well understood vulnerability that its no longer one.
I remember TEMPEST, from my early days. Not very well though. Wasn't it what the Americans used to use? We (Wang) had equipment in USAF bases here and I'm sure that was TEMPEST.
TEMPEST is the standard applied to electromagnetic shielding of electronic equipment. I'm pretty sure that it originated in the US but was then adopted by the UK and other allies.
I worked on a few projects for the MOD that specified TEMPEST certified kit. The first one was a digital data and telephony setup between the three allied sectors in West Berlin around 1985 or so.