Using find/change to remove text sometimes affects paragraph styles

I'm using find/change methods in CS6 to remove large swaths of unwanted content in documents and it works well and fast.  Only one problem:  The applied paragraph style of some the remaining content changes to another paragraph style, which is undesired.   I want to maintain the existing paragraph styles of the remaining content, even as other content is deleted around it.

In my case, I'm removing content matching a given condition.

var myDoc = app.activeDocument;
app.findGrepPreferences = app.changeGrepPreferences = null;  
app.findGrepPreferences.appliedConditions = ['Content with this condition is removed'];  
myDoc.changeGrep();

I would greatly appreciate your suggestions for removing the content without affecting the applied paragraph styles of what remains.

Thanks,

Jon