From the article you posted:
One major argument in keeping the list classified has been that it only specifies individuals who have allegedly been in contact with Stasi, but not the nature of the contact. Therefore being on the list would not constitute proof of or even indicate breaking any Finnish laws. Consequently it was chosen not to shame potentially innocent persons in the media.
So, no, it’s not good evidence for what you imply. Although the article mentions (without citation) that those on the list " are popularly described as having been suspected of spying for the Eastern Bloc" it doesn’t specify that they’re affiliated with Finland’s leftist or social-democratic parties.
