I think intolerance towards other peoples democratic voting choices decides whether one is a decent or not very decent person.
This is just as silly and black and white a position as refusing to associate with someone who votes differently than you. Decency runs much deeper than that.
What makes a person decent or not is their actions and, really importantly, the values that underpin those actions.
So, for example, I can’t see any values that I would consider decent or that I would want around my kids that would be compatible with BNP voting (back in the day).
In the recent election (and in all elections, particularly in a FPTP system, but this one particularly so) there will have been a range of factors that determined how someone voted, from ardent devotion to a cause to ‘this feels like the least as of some shitty options’. So yes, it’s daft to dismiss someone solely on the way they voted.
It’s equally daft to say that people’s politics are totally irrelevant, because they are linked to underlying values. There is a huge spectrum of political opinion and the values of those at the extremes of those opinion are something I don’t want to associate with, TBH. Because those values are in conflict with my own.
It doesn’t sound like the grandparents are particularly decent people - rude, intolerant, and disrespectful of others, believe poor people are the sole architects of their plight and there are no children suffering as the result of poverty. That is not how all Tory voters think by a long shot. The vote isn’t the issue, it’s what lies under it that counts.