Hey - prior to removing these ways I asked other local mappers for their opinion regarding 'proposed' ways. The general consensus was that 'highway/railway=proposed' ways are not appropriate for OSM as they are not verifiable on the ground, and as you mentioned, the route is subject to change. The 'proposed' value itself is a disputed subject on OSM (see https://wiki.openstreetmap.org/wiki/Talk:Key:proposed#Verifiable? and https://wiki.openstreetmap.org/wiki/Tag:highway%3Dproposed)

Once construction starts, it would be valid to add the ways as railway=construction.

If you disagree, you are welcome to join the OpenStreetMap Slack #local-minnesota channel and voice your opinion. This changeset (and/or 134796569) can be reverted if there is agreement with others.