Thanks! But according to the rules in your reference, I would say that 2) is correct. So why does the google search give more results for 1)?
Maybe that link has a rather BE view. Searching only UK pages I get:
Results 1 - 10 of about 720 for "whom we can rely on".
Results 1 - 10 of about 562 for "who we can rely on".
Or maybe it's not so much 'a BE view' as a 'formally impeccable' view. What Google picks up is not what is formally impeccable, but what people have typed - regardless of their status as English speakers.
______________ Note that, Google is great search engine; true, its hits reflect spoken and written English, but those hits can't tell you why speakers use a given form or, for that matter, what dialect they're using or whether they're using Standard English or not. So, next time you google, you may want to take that into consideration.