I have two questions for y’all.
The system you have attached would have similar concerns. It is not entirely clear how much section and what material the barrier modification you sent was. We would believe that the effect would on guardrail performance would be less if the material had lower strength and/or section.
An alternative would be to install a separate, low-height fencing as denoted on their website 1’-2’ behind the barrier. In that case, there would be little concern.