Imagine having anti-boycott laws.
If a person, company or country does not want to deal with another company or country, it should not have to. If you don't want to be boycotted, you shouldn't have done actions that would warrant boycotting. This takes away a valuable tool for forcing entries from taking accountability.
The US does the same thing themselves, albeit by different means, when it tries to punish other countries with tariffs.
And what about the restrictions of Gaza from being able to get food from literally anyone? Something that escalates the effects of boycott / sanctions to a literal blockade. An act of literal genocide? Does that not count more as a unilateral and obvious threat than poor Israel, unable to buy as many weapons as they used to?