Mr Cable said he welcomed the defection of East Renfrewshire councillor David Macdonald from the new Change UK party, and declared him a "sensible guy".
And Cllr Macdonald said that he "absolutely" stood by his remarks, and that "96 per cent of Scots probably agree with me."
The Scotsman revealed today that Cllr Macdonald had written a lengthy Facebook post saying he would do whatever was required to “neutralise the situation” if his home was broken into. He added that it was “pathetic” that the legal system would “not back you up if you kill someone in the act of defending yourself within your property”.
In South Queensferry to launch a new European election poster with Scottish Liberal Democrat candidates - and Cllr Macdonald - Mr Cable said: "I welcome David's endorsement and his realism about Change UK's prospects."
Asked about Cllr Macdonald's controversial remarks, he said: "I don't know the detail he'll be able to answer. I don't know what happened, I've had a long talk with him and he seems a sensible guy, fully aligned with our values."
Commenting on his defection, Cllr Macdonald said: "I'm very proud of my time working with Change UK, but it became blindingly obvious as the campaign went on that we were so close on message that we were fundamentally shooting our closest competitor in the foot in Scotland.
"I wanted to do what I possibly could to realise that the strongest contender now needs our backing."
As to his Facebook comments he said: "I absolutely stand by my views when I have made them public. And I believe around 96 per cent of Scots probably agree with me."
Mr Cable said he was feeling positive about the Liberal Democrats campaign in the European elections - and warned of the "dangerous fallacies" of Nigel Farage and his new Brexit party.
"The feedback I've had from my Scottish colleagues has been very positive, it reflects the mood across the UK, or the parts I have been to, we're getting a strong upswing," he said.
"The Brexit Party is actually bringing together the Brexit vote but we've got to expose it. There's a lot of very dangerous fallacies Nigel Farage is putting around that somehow or other we can just drop out of the EU and adopt WTO rules, and it's completely untrue. There are no rules, there's complete anarchy out there, there's a trade war breaking out, and these people think Britain can wander on it's own into the wild world. It's a dangerous simplistic doctrine and we've got to confront it."
He also said that those against Scottish independence should not be swayed into voting SNP in the Euro elections because of its Remain message. "We have a totally different approach to the SNP - we want to stay in the EU but also in the UK
"The two things are linked because we've realised with Brexit, the amount of upheaval it causes and when you try to unscramble a relationship of 300 years the potential for disruption is even greater - and the sense we get is that people in Scotland see the connection and like the formula we have."
He said that Labour was losing ground "because of the ambiguity Corbyn has adopted sitting on the fence. We've been crystal clear, and people don't want fudging on the biggest issue of a generation. The Labour party has tried to be pro Remain in London and Scotland and pro Brexit in the north of England and you can't do that - the lack of clarity is costing them dearly."
Addressing Lib Dem campaigners and candidates, Mr Cable added: "I think we are actually fighting these elections, unlike the Tories who have given up and the Labour Party who are just embarrassed and sitting on their hands.
"You've got one serious source of competition up in Scotland but we've got to campaign and I think we're winning the argument and we want to get the votes as well."