Strange StopPublish behaviour, maximum 10 years from StartPublish if set to null on save

Hi!

We have an import job that creates variants and products. Some products are old and have a StartPublish date like 2001-03-01. When this product is synced we set StopPublish to null but then Commerce sets StopPublish to StartPublish + 10 years. Why is that? Should this be considered a bug?

/Kristoffer