I wasn't supposing that the insurrectionists would succeed in murdering Pence, or that the entire Republican party would unanimously back Trump, just that enough Republican-run states would raise questions about the legitimacy of the (replacement) electoral certifications (which they might refuse to produce) in order to trigger the contingent election.
In such a circumstance, it's hard to imagine the state delegations of Republican states deciding to throw away a perfectly legal and constitutional opportunity to elect their guy to the presidency. If it makes you feel any better, I would expect Democrat delegations to vote for the Democrat candidate if there were ever a contingent election, even if that candidate didn't have a plurality of electoral votes (perhaps at least justifying their decision by pointing to the popular vote, which their candidate might nevertheless have won).
In such a circumstance, it's hard to imagine the state delegations of Republican states deciding to throw away a perfectly legal and constitutional opportunity to elect their guy to the presidency. If it makes you feel any better, I would expect Democrat delegations to vote for the Democrat candidate if there were ever a contingent election, even if that candidate didn't have a plurality of electoral votes (perhaps at least justifying their decision by pointing to the popular vote, which their candidate might nevertheless have won).