What are the disadvantage/consequences of moving updated column to separate table to prevent table lock on the original table?
From what I remember about this database from your earlier questions, I'd suggest you look at these alternatives to your approach:


Consider RCSI or Snapshot isolation. This will prevent your select queries being blocked during the update. Be mindful of the increased usage of tempdb this can generate but IIRC the nature of your database/data should mean this is small.
Updating the points record in batches, rather than one almighty transaction for the entire table. See How to Use Batch Size to Speed Mass Updates, Inserts and Deletes for an old (but still relevant) approach.