While redirecting or displaying something based on the referrer is a cool concept, it won’t work. Referring traffic from google maps shows up as direct traffic

While redirecting or displaying something based on the referrer is a cool concept, it won’t work. Referring traffic from google maps shows up as direct traffic unless yiu specifically add tracking code, which the OP can’t do. The only way to deal with this is to get the listing removed. Use The google my business redressal form to do that.