Why is it surprising that it isn't fatal? They picked relatively rare codons, and they slotted the changes in sequentially. The process of inserting dna is se

Why is it surprising that it isn't fatal? They picked relatively rare codons, and they slotted the changes in sequentially. The process of inserting dna is selective (plating lawns of bacteria and picking colonies), probably the fastest growing colonies had the opportunity to build in compensatory mutations if there were subtle secondary or tertiary XNA features that were mildly deleterious.