I see your point and I did think (personally) the three years was a bit light - for reference the Americans say six years (I think) but do allow some things (like working for UN organizations) that amount to somewhat broader in some cases.
But I don't think worth arguing about the specifics - at least not too much, and mostly not at this stage. There's always going to be some collection of case-specific factors that some are going to feel "shouldn't" be allowed, and vice versa. We already get that with just about every program we have.
To me the more important test - are most clear cut cases going to meet the test, and at least some logic to the cut off (eg most who don't meet the test clearly well short of 'substantial connection'? And I could argue for exaclty how many years, some additional tests like you say, sure, something a bit more substantial than a day count over 30 years. But I could also live with what's mooted so far - if they made it three or five or six or eight I'd also be mostly fine with it.
More important to me is the principal.
[BTW as for your proposal - nope,don't like it; I wouldn't have met your test when needed due to the 'last ten years' thing - even though I lived in Canada for about 30 years, all my education through undergrad, and work in career public service for several years. Don't see why the 'in last ten years' is that relevant, although can see some years as an adult, roughly what the Americans do.]