In an interview with Scotland on Sunday, Carmichael also said that Unite’s decision to fight a bitter industrial war with Ineos, the owner of Grangemouth, “played into their hands”, ensuring the firm won everything it wanted.
Meanwhile, he criticised the “vilification” of Ineos founder and chairman Jim Ratcliffe, saying personal attacks on his character over the past two weeks had been “unhelpful”.
Carmichael was speaking after Ineos announced on Friday that it had agreed to fire up the huge petrochemical and refinery plant after Unite agreed to a no-strike pledge and to reforms to working conditions.
The move ended a two-week stand-off which, on Wednesday last week, put as many as 800 workers out of a job, and threatened up to 13,000 across the central belt.
Yesterday, Grangemouth’s site manager Gordon Grant said that it would take two to three weeks for the site to re-open fully, following the dispute.
The crisis led to an unprecedented show of unity from ministers in London and Edinburgh as they attempted to convince Ineos management to accept a deal.
However, with the referendum on independence now less than a year away, Carmichael last night claimed that the affair had bolstered the pro-UK cause.
“I think actually it demonstrated that the constitutional position gives us the best of both worlds; having a government in Edinburgh which is able to connect in the local position in the way that it did, and having a government in London which is part of a national set-up, that can stand behind the sort of deal that we were talking about at Grangemouth.”
Had Scotland been independent, he said, the UK Treasury would not have stood behind a loan guarantee of £130m.
However, SNP government officials said that the Scottish Government would have done so in those circumstances, and that it was currently prevented from doing so by Treasury rules.
Rebutting Carmichael’s claims, a spokesman for First Minister Alex Salmond said the affair had also exposed pro-UK claims that SNP ministers had left the country “on pause” as they campaigned for a win.
Sources said Salmond had dealt personally with Ratcliffe last week to let him know that Unite was now prepared to accept the firm’s demands in full.
The spokesman said: “The last few days have totally demolished the bogus claims of [Scottish Labour leader] Johann Lamont and others about this Scottish Government’s priorities.
“The only thing on hold in recent days was the First Minister’s involvement in his own annual party conference and campaigning in the Dunfermline by-election – because he and John Swinney were instead devoting huge time and energy to securing jobs and livelihoods for hundreds of workers at Grangemouth, their families and communities.”