If the person in question has never had the need to know iptables, why would that change now?
If a job will require such knowledge, they will pick it up. Iptables is exposed as a facade to nftables, lots of the concepts just transfer over, just that iptables is the more antiquated option.
I for instance have never really used iptables in anger, but have lots of experience with nftables and pf. I’ve used both in a professional setting. People can be made aware of iptables, but unless there’s a need to know it, I wouldn’t recommend picking it up now. And you’ll know if you need to learn c++17 or iptables, or python 2.7.
For more context, I've been working pretty closely with firewalls on all desktop platforms, and I've been doing so since 2018, and I've never had know about iptables on Linux.
I for instance have never really used iptables in anger, but have lots of experience with nftables and pf. I’ve used both in a professional setting. People can be made aware of iptables, but unless there’s a need to know it, I wouldn’t recommend picking it up now. And you’ll know if you need to learn c++17 or iptables, or python 2.7.