I’ve only ever heard two kinds of arguments or implied arguments about laws which enforce job security

(1) From the worker-perspective: they are good. Job security improves quality of life, peace of mind, etc.

(2) From the company-perspective: they are bad. Job security hinders flexibility, stops rapid responding to changing economic conditions, etc

Now I’ve only been passively absorbing information on this and I’m not claiming to have made anything like an active search for alternative arguments, but I suspect that the fact that I haven’t encountered a third kind of argument reflects the fact that it isn’t made as often, or as clearly-

(3) From the company-perspective: they are good. Commitment to job security encourages companies to seek out sustainable and stable business strategies.

Not just good, but good for everyone! I wonder if the argument isn’t made because it is a two-time point / second-order kind of argument, rather than a simple ‘If X happened i could/couldn’t do Z’ kind of argument. You need to represent a more profound kind of counter-factual to think about this third line of reasoning; not just if the company needed to downsize it couldn’t, but because downsizing is harder the company would alter circumstances so that it would be less likely to need to downsize.