Is anyone seeing this phenomenon when doing a search that doesn't contain the 301'd domain name?
Otherwise, I don't see a problem. It's targeted at those less web-savvy people that still search for domain names.
There's a reason you or your client purchased these domains, right? If you changed domains, you still want to be found by those folks. Seeing a result they're not familiar with may turn them away. If you own a number of domains to prevent typo-squatting, it's beneficial to see the domain they typed in. They may have misremembered the exact spelling and would be reluctant to click on the actually correct result.