Basically that just means that they won't travel to or even be invited to countries that would arrest them.
The same goes for Putin.
A lot of pro-Israel people just think the ICC is just a tool used by countries that hold a grudge against Israel and don't take it seriously (e.g. the Biden administration released a statement condemning the ICC when they announced they were seeking the warrants), so having more first-hand witnesses stating clearly that war crimes are happening is relevant.
Ideally we'd have journalists reporting these things, but Israel blocks those from entering Gaza too.