The danger is that (to quote Jurassic Park) "life always finds a way", and the risks are massive.

A good example of the risks of mirror chirality is thalidomide - thalidomide has two enantiomers (one that provides sedative and anti-nausea effects and another that causes the infamous thalidomide birth defects) which the human body naturally flip-flops when administered.

The risk to reward ratio is negatively misaligned (edited) when factoring the catastrophic risks and how easy it would be to weaponize (either on purpose or inadvertently).

No such thing as a too-low risk to reward ratio. That's basically free rewards.