Was Starmer right to appoint Mandelson as US ambassador despite vetting concerns?

Keir Starmer appointed Lord Mandelson as UK ambassador to the US, but he was sacked seven months later. Tories accused Starmer of misleading MPs on the vetting process and pushed a motion to refer him to the Privileges Committee. The House of Commons voted against the motion 335 to 233, with most Labour MPs opposing it.