IMO events in Gaza could derail Starmer's attempts to be a government in waiting.
There are around 15 or so Labour MPs who are Muslims. The article below shows how the current situation could cause internal problems within Labour:
Apsana Begum left the party’s Liverpool conference after the Tory chairman demanded she have the whip withdrawn. Rivkah Brown reports.
novaramedia.com
And of course it isn't only Muslims who won't be happy with Starmer's support for the horrors in Gaza and its going to make their persecution of Corbyn supporters for supporting Palestine look very bad.
The fact is,
6% of the country is Muslim and they are politically overrepresented within the Labour Party. Support for what could turn out to be a genocide against the Palestinians will almost certainly throw Labour into renewed chaos.