Oh dear. What is Corbyn playing at? What the hell does he think he’s achieving with this? Very poor judgement indeed.
We’ve had the argument about the circumstances before, so I’ll try and be relatively brief.
As a fundamental point, The SNP weren’t, and never will be, obliged to have confidence in a Labour government. Callaghan’s or otherwise.
But there’s more to it than that.
Callaghan himself blamed the rebels on his own benches, rather than the SNP, for ultimately bringing about the collapse of his government.
The Labour rebels referred to by Callaghan in this instance are those who carried a last minute wrecking amendment to the 1979 devolution referendum in Scotland, tabled by a Labour MP, introducing the requirement for approval by 40% of the whole electorate as well as a 50%+1 simple majority in the result - making it effectively unwinnable because
_the register was so out of date that even in an area where major support for a “yes” vote might be expected, achievement of 40% of the electorate was virtually unattainable. This was because the majority of electors lived in older tenements or newer Council blocks of flats where flat numbers were not specified. The work of electoral registration staff to obtain an accurate current register was almost impossible. _
Note that that 1979 result was 52:48 in favour of devolution.
Not being pro-Labour is not automatically being pro-Tory. And the sooner Labour realise that, the sooner they’ll have a chance of governing the UK. And they may even move on from being the third party on Scotland.