Well, I guess it's time for me to swoop in and play Devil's Advocate?
To a certain extent, anyway.
First things first.... I think it's something the three of you should decide on together. It's not fair for you to take the brunt of the responsibility here... because it will come around to bite you in the ass.
If all three of you agree to pursue the crush, whilst accepting joint responsibility for what happens if it all goes sour.... then I think it would be ok to go ahead.
I don't know what their work situation is like, how well they get on at work, how important/rare their jobs are, etc. To be honest... in terms of work... it's kind of up to the two of them. It's their careers.
I do understand what you are saying about crushes - especially inappropriate ones. I have a huge crush on my girlfriend's daughter's music teacher, who we see for an hour a week for a parent/toddler hippie dancing around embarrassing thing. It would completely inappropriate to ask her out and if she said no, I'd have to see her in class every week. But damn, I don't think I've found anyone as attractive in a few years.
Sometimes there are those special crushes you just wonder about more than others.
Ok, so, bottom line in my opinion... they have to talk about the work repercussions and all three of you have to take an equal responsibility for it to be worth the risk.