I have a client that has a house in NY (primary) and a home in PA (vacation). As of March, he has been living in his PA home. He still works in NY (remotely) and goes to NY to check on the home once a week. He hasn't updated anything to the PA address; license, bank account, registered cars. He plans on moving back to NY once the pandemic is over, whenever that may be. Will I be making him a nonresidence of NY when tax time comes or will he still be considered a resiednce since he maintains a home there.
You stated he goes back to NY every week, so he has not been away from his resident for the 183 day rule. Although the rules vary among states, generally speaking, most states define a “resident" as an individual who is in the state for other than a temporary or transitory purpose
As @sjrcpa replied, he could be considered a duel resident, but you stated that he is in Pa only temporary. I don't know how Pa works, but most states do not consider you a resident if you are there only temporarily.