Ich,
The electorate voted for a Conservative Government, albeit one with a slender majority. If the opposition call a vote of no confidence, and win, then the electorate have been cheated out of their democratic choice. It might be legal, it might be procedurally correct, it might even be justified, but if the Country finds that Corbyn is Prime Minister, when they clearly didn’t vote for that, then it will be perceived as a Coup, and Labour will be punished for its power grab at the shortly to be held General Election, leading to 5 years more of Boris.
Labour should be patient, wait for events to proceed naturally, and capitalise on the consequences.