If we're going to be picky, then both of you have a point if you properly look at "risk".
Anyone who has done any risk assessment training at work will know that "risk" is the combination / multiplication effect of "a thing that could happen / go wrong" and "how bad could that thing be".
And to reduce the "risk", you reduce or remove or change any combination of things involved. So, overall risk is in theory reduced by by having fewer people involved (2 people in car means 2 people could get injured, only have 1 person in car, you've removed one person from the equation). But equally, a short(er) distance might reduce risk - to counter the point above no, accidents don't happen just in the places you plan for them to - but only doing 20 miles rather than 50 or 100 reduces opportunity (if all else is equal). Obviously it doesn't reduce as much as only doing 10 or none .....
And then relative to going on holiday or doing a big shop - what's the difference to that kind of heavy stuff versus this? If it can't be tied-down securely, that's a different story. Depends whether you think you know nothing about it, so don't think about it - or because it's so different to what normally goes in the boot, you're extra careful about tie-downs.
Not an exact rule, but if its something that can safely be tied down / secured in the boot (and doesn't impact the balance / safe load of your car), then it sounds reasonable. If every other person who carries this ram has a specialist kit installed in their works van for a reason, then its probably not a good idea.