Every major sea voyage of the past had a cat or two, they were necessary to keep rats from eating all the food supplies.

Apparently the cat on board the expedition that discovered New Zealand immediately upon reaching land jumped out and grabbed a small flightless bird (then a brand new species discovery) and dragged it on board to eat.

Cats have been a menace to the native kiwi birds ever since.

Ocean ships have rats so they would tend to have cats even if people didn't encourage them.

With the COTS technology of cat diapers I think they could have a pet cat on the ISS but they don't want the risk that it goes wrong and they'd have to put it down.

There's also the smell, by all accounts the ISS already smells a little bad from decades of BO and grime, I would not want to add the smell of cat shit to that.

do not worry, we will discard whole it soon...

The decommission date gets pushed back any time it gets close I doubt it will actually be considered until there's major structural issues. The time always seems to be "when we have a commercial alternative" which is economically a pretty long ways off from the looks of it.

I think the bigger problem is for a cat to survive g-force on launch

I doubt cats have a substantially harder time surviving g-forces than humans. Smaller animal should be less affected; plus, commercial manned launch g-forces are going to be pretty low peak anyway. Maybe 4G?

And loving pet owners will want to note it did not end well for the cat