"An employer paying into a SEP isnt considered being "covered by a retirement plan" for IRA contribution limits for the taxpayer." If they make a contribution for you, you are covered.

Unless the W2 has the retirement box checked in Box 13, he should should be able to contribute to an IRA (assuming he meets all the other qualifications)...its too late for a 2019 IRA contribution though, so this may all be moot.  Agreed.