Surely a government minister should be thick-skinned or professional enough to not stick the finger up to perfectly legal protestors in a situation where she is surrounded by cameras?
Government ministers make decisions that affect real people on a daily basis and not always positively. If they aren't prepared for the backlash then don't choose politics as a career, frankly, and certainly don' become a minister. I think people affected or angered by those decisions are perfectly entitled to show their unhappiness at that person who is making those decisions by protesting, even if it's loudly or insulting. Why is there a need to bow down to politicians, especially ones who willingly make decisions that may have severe consequences for ordinary people? Someone working a shop for minimum wage gets abused and they'd be sacked for doing such a thing, but a government minister earning tens of thousands of pounds a year on top of their MP salary, plus god knows how many other streams of income, is somehow not able to cope with some people shouting nasty things at her? A musician playing to a crowd is perfectly entitled to make a political statement too, indeed music is a huge form of protest. Making anti-tory statements is hardly a shock at a music festival where the mostly young, Scottish crowd is hardly going to be made up of tory fans. I'd go out on a limb and even say most people there detest this government. Performers know their audiences.
If a government minister would rather stick the finger up to those disagreeing with her rather than attempt to engage with them then maybe she shouldn't be a minister. She is there to govern for all, not just her voters.
The supposed death threats she reviews are something else, those are illegal of course, and will be dealt with by the police. Death threats are not a form of protest.