I think this is good advice. If for no other reason than to make it much more likely that they will give you a good reference. Even if they said you don't have to do anything for the next 60 days.
That won't make any difference in terms of "references". If his boss isn't assigning him any work, there's no work for him to do. TPMs have to be assigned to projects. If he's not assigned to a project, there's no work for him to do. He may need to transition his projects to others (do some knowledge transfer), but if they're laying off TPMs, they're probably going more to a self-managed (scrum/agile) scenario where the remaining project members will just self-manage, and they already have the requisite knowledge to keep it moving.
I was actually on 2-3 projects which had a PM on them who was dismissed from the company. We simply carried on without a Project Manager, since we just filled the gap that was left ourselves. We know more about the details of what needed to get done, when, etc. than the PM did.
I think that people are misunderstanding the nature of this work. It's not like working in a factor or an assembly line or doing other "concrete" work.