This looks like an attempt to present a kind of Potemkin nationalisation to mollify the anger of people with £1k+ season tickets and cement their hold on voters drawn away from Starmer in the last election (who meekly dumped rail nationalisation as a policy).
This measure might be too little to really matter but the fact is that when you don't have an market(and for passenger rail you kind of don't) outsourcing operations to for-profit organisations provide nothing but a venue to funnel cash out of the system to private shareholders.
When there is an functioning market that is not tied to an government backed/guaranteed service it does make sense to subcontract work to private enterprise, but unless the government contracts represent a relatively minor portion of the subcontractors revenue and the subcontractor don't have more then say 20% market share, there is no functioning market, so all you end up with is an mercantilist structure of public risk and private profits if you still insist on pushing the task to private enterprise.