Hi gogi,
You can achieve this with the help of repeating sections. Add your list as secondary data source with the needed fields. Place this Data on to your form, select Section with controls as the option. You will see that it creates a repeating section.
Now you have to apply the filter on the section itself and not on individual fields. Once you have saved the username with the help of GetUserProfilebyName web service, compare it with the column in this secondary data source. The rule on the section would be:
Formatting > If (Username from GetUserProfilebyName != username from secondary data source column), Hide. Hope it helps.