Exactly. Temporary pay sacrifices (even significant ones) are fine and I think most have been more than happy to accept them, and will accept more, lasting as long as the crisis lasts. This is an unprecedented situation and we all know that.
Permanent cuts to terms and conditions are a different story and would simply be opportunistic cost-cutting. When things pick up again (and they will) you won’t ever be getting those back.
If they need more cost cutting than that, then they have to start getting rid of people (which I suspect they need to do, regardless). How they do that is up to them.
Until then, stop offering up your colleagues’ terms and conditions on the sacrificial altar.