Defining a column as nullable in a view (but not in the referenced table)
Yes, it's possible:

select Id, -- Remains as in table
  cast(MandatoryIntCol as int) as [MandatoryIntCol], -- Makes nullable
  isnull(OptionalIntCol, 0) as [OptionalIntCol] -- Makes mandatory
from dbo.MyTable;


It's worth noting that there are some restrictions with this approach:


The changed columns are not writeable in the view, so if the OP's application tries to write to them, it would fail.
The application must not try to distinguish between tables and views. Most apps do not, but annoyingly, some product applications do.