Not sure where you read that but I doubt it has much validity. There is really little scientific proof behind so-called 'companion plantings'. Most are just folklore or old gardeners tales/gardening myths. I wouldn't let the proximity of either govern where I planted them, other than to make sure the tree was out of shade casting range.

There is a UC Master Gardeners publication that addresses this topic - interplanting a home orchard with vegetable crops. No concerns about placement were presented at all and both tomatoes and peaches were part of the mix.

Thank you! I had read it in several articles. “Apparently” it’s a risk for blight. Thanks for your response.

I know of no blights shared by both peaches and tomatoes. Plant diseases are typically rather plant specific or at least family specific. The common tomato blights are family specific so not sure how peaches factor into that at all.