My assumption is based on:
"he went away a few weeks ago on holiday and during this time his work visa expired, due to an oversight from him and his company"
If he was on holiday and his work visa expired there was no oversight on his company's part unless he was still employed by them.
And if he arrived back and has been on a tourist visa but not working, there should be no concern over:
"this all comes as he's about to transfer his visa to another company"