The Guardian article mentions that nurses are exempt. Are there other exemptions? For example, most post-doctoral scientists earn less than that. Does that mean non-EU citizens cannot come to the UK to work as a post-doctoral scientists?
According to the Tier 2 guidelines, the current salary requirements are:
You’ll usually need to be paid at least £30,000 per year or the ‘appropriate rate’ for the job you’re offered - whichever is higher.
What constitutes an "appropriate rate" for various occupations is listed here. Table 1 lists PhD level occupations. Depending on the field and experience, the required salary for a post-doctoral researcher ranges between £21,600 and £28,000.