As an FO, I'm not sending any ill will to any one specific IP in this situation. I do fully believe that you were asked to fly the line by the folks that run the airline. From all I've researched on the subject, it wasn't a decision that the IPs made. I have, however, lost quite a bit of goodwill towards the company for making the decision to get through the summer by any means possible without bringing back any of the FOs that are currently on the street. Despicable actions like this are how businesses bring collective bargaining from their labor force upon themselves.
From your perspective, I know it does not seem fair. However, if it keeps this company afloat, then being one that is still here, I say do what you need to do. Bringing back pilots for 3-4 months would have cost more money, and I doubt many would want to come back with the guarantee of being on the street again in the fall. That would be despicable! I hope not, but I am guessing that there will be 57 more on the streets in the Fall.
So far as the IPs flying as FOs, however, I do strongly believe that they should be paid as FOs. I understand that in several people's situations, it was in their best interests to fly as an FO rather than as a Captain. Let's face it, being an IP with the seniority on the FO list to pick the schedule that you want, have very little responsibility, yet still get paid as a Captain, is a good deal for the IP.
However, if forced to accept the pay of an FO, I doubt that any IP would have accepted the assignment. Let's play the devil's (management) advocate here: using the logic of helping the company to accept this (?) temporary assignment, why not really help the company? Obviously this assignement was meant to limit costs, why not really help the company out and accept FO pay for FO work? Get where I'm coming from as an FO?