In this particular case, the mutation being added to the original SARS-CoV-2 is one that was already present in Delta. So if someone were to replicate this wit

In this particular case, the mutation being added to the original SARS-CoV-2 is one that was already present in Delta. So if someone were to replicate this with real virus (as opposed to the non-infectious particles the existing experiment used), and the virus were to escape, it seems like the new variant's infectiousness would likely be somewhere between the original and Delta. Which means it would get outcompeted by Delta and the effect on the population would be nil. There's no guarantee of that, so biosafety is still critical, but as biosafety worst-case scenarios go it seems relatively ho-hum.