Removing the support is "wrong". Here is why:

Example 1: Consider a header with three identical branches to pumps. Two branches are operational, one is standby. In an operating branch, a +Y lifts off. Removing this restraint for the analysis is incorrect for the standby line.

Example 2: Consider a system with more than one operating temperature, where some supports lift off in some, but not all, of the operating load cases. Removing these restraints is incorrect for those cases where the pipe would sit on the restraint.