Rex cetera ut orsus erat peragit

Orberg LLPSI Cap XLIII (again). Tullus is condemning Mettius for treason:

Centuriones armati Mettium circumsistunt. Rex cetera ut orsus erat peragit:

I’m perplexed by the sentence Rex cetera ut orsus erat peragit:

I can sort of deduct that Mettius gets up to speak but how does the Latin work? Here’s my reasoning:

Rex (the king) cetera (whilst) ut (in order to? to? so that?) orsus erat (had arisen) continues:… mmm

Cetera I think means ‘at the same time’ or ‘simultaneously’.

OK so to change the word order to help understanding it would be> Cetera (at the same time), orsus erat (he had arisen) ut peragit - (it’s not subjunctive so does it mean as or while?).

At the same time the King while continuing had arisen (to pronounce a decision?) [and] continued….

Cetera (neuter pl.) is the object of peragit. “The king completes/proceeds with the rest [of his speech] as he had begun.”

Ut with indicative means “as” here–it doesn’t introduce a purpose clause, which would require the subjunctive.

orior – here, “begin.”

Lewis & Short, orior;

II Transf., in gen., . . . > to begin, commence, take its beginning: ab aliquo sermo oritur, Cic. Lael. 1, 5

http://perseus.uchicago.edu/cgi-bin/philologic/getobject.pl?c.13:1443.lewisandshort

Thanks.