Unless they are proposing to escort returning travellers home then anyone who doesn't drive and park at the airport could be spreading the virus on public transport.
However it does mean that people intending to stay for longer periods could still come, for example my dad was considering coming to help out with my baby for a few months, and people planning to move to the UK wouldn't be excluded (obviously they haven't actually been excluded yet)
From what I have read the UK measures wouldn't apply to Ireland, which probably makes sense unless they do a Brexit-like deal where NI is isolated from GB.
Well it looks like my business travel plans of 1-2 day trips to various European countries within a short period are even less likely to happen now - was hopeful that they could happen in July/August