Not that HIPAA applies in the UK (and at this point it's not even certain that Google can be GDPR compliant even it they wanted to) but that bit you quoted appl

Not that HIPAA applies in the UK (and at this point it's not even certain that Google can be GDPR compliant even it they wanted to) but that bit you quoted applies to G Suite customers who have to enable that thing in the account settings. It is implausible that every hospital, clinic, lab and other medical organization in the UK would sign up to G Suite and deploy it to every of their employees; or that the British government would negotiate some kind of procurement contract with Google quickly for all that to be practical. Absent those issues, Google Sheets has a limit of 18k columns and 5m total cells, in this case the issue was that they hit Excel's 16k column limit. Not much of an upgrade there.