Is it frowned upon to have check constraints only applicable to a subset of rows?

At my place of work we are running into an issue, we have many parameters stored in a table like so. | ModelParameterValueID | ModelParameterID | ModelID | CurrentValue | Updated Date | | --- | --- | --- | --- | --- | | 187883 | 81 | 10849 | TEMPSTR | 26-Jul-24 | ModelParameterID = 81 corresponds to a string parameter in our database. Our technicians have some models that need the CurrentValue nulled, but only for that modelParameterID. We have a CHECK in place that makes sure CurrentValue is not Null, so I surmised to myself that if we could have a conditional CHECK that allowed CurrentValue to be Null only if ModelParameterID = 81 then this issues would not be there. So I contacted our database administrator and asked him if a change of this kind would be possible. He said > It is not good practice to have a constraint defined like that based on a particular value in another column. I asked him to explain but he would not. Could someone explain as to why something like this is frowned upon? And if it indeed is not good practice, then what would an alternative be?