The MP wants all staff at SNP headquarters to be paid-up party members. What's wrong with that? It's perfectly natural for managers to want employees to support an organisation's product, especially when that "product" is ideological.
Of course, the Scotsman correspondent who writes that Mr Salmond and his supporters have:
so little regard for employment law that they believed they could force workers into changes to their terms and conditions without consultation or negotiationis probably correct.
Nevertheless, employers should have the right to lay down whatever conditions of employment that they see fit. Equally of course potential employees can go elsewhere if they don't like the proposed rules. Let the market sort out terms of employment.