Yes, he can be interfered with.
Let’s say Artie throws the ball to Bill, who then laterals the ball to Chris. When Bill first catches the ball, defenders can legally slam into Chris, well before Bill could pass the ball back to him.
I’m pretty sure that rule is recent, as in sometime after 2000.
I’m pretty certain you are wrong, and I’ve been watching professional football for some 50+ years. 
It’s not easy at all to dig up a cite for when a rule was instituted, but the best I could do says that not only are you correct, it’s probably been even longer than that. Cite:
The most interesting bit I got from that (possibly shaky, but seems legit) second-hand cite? The rule where injuries cost you a timeout in the last two minutes (1939) was instituted 10 years before the “two minute warning” itself was instituted. (1949, according to that same cite.)
Note that I’m equating the “fourth timeout” rule as being the same rule as costing a timeout for injuries inside the last two minutes of a half. They aren’t technically the exact same rule, but they are related so closely as to be a reasonable assumption.
There have been scads of US football players who have come north thinking this, and that they’ll have an easy time here.
Those are the ones who tend to get cut early in the season.
I love Canadian football; when we first got cable TV in the early 80s, the CFL was a staple on ESPN. And, I totally agree – while it’s superficially the same game, the specifics are different enough that it’s clear that successful players have a different mindset from playing American football.
I think that’s because there are many players who ended up in the CFL with success after problems getting a career going in the NFL. Warren Moon is a classic example. Moon played college in the US, and played well, but went undrafted in the NFL so went to the CFL instead, where he was an outstanding star. Of course, Moon also went to the NFL later and was great there as well (and is in the Hall of Fame) so he’s probably more an example of someone that the NFL undervalued rather than a player who couldn’t cut it. But there is still the impression that the CFL was a “developmental” league for Moon until he was ready for the NFL, leading to the impression that the CFL is “easier”.
I don’t think the CFL is easier, it’s just different. And I’m sure many players who succeed in the NFL would fail in the CFL environment.
I suspect that the experiences of Moon, among several other quarterbacks, has reinforced that impression.
While it may be difficult to say for certain, it seems likely that Moon’s race was a factor in his not being drafted by the NFL (and I believe that Moon was certain that it was a major factor); in the 1970s, there was still a commonly- (if quietly-) held stereotype that black QBs weren’t suited for playing in the NFL – that they tended to be athletic, but lacked football intelligence.
A couple of other examples that play into that impression of the CFL were Doug Flutie and Henry Burris, two American QBs who had considerable success in the CFL (both of them were multiple winners of the Most Outstanding Player award), but who were not nearly as successful in their NFL stints.
I was responding to the comment that the CFL is 99% the same as American football, not the calibre of the players. Yes, the QB position is almost always an import from the States, but even then, for every Warren Moon, there are numerous QBs from the States who have very short careers in the CFL.
From the perspective of a rugby fan who doesn’t know either game, they are 99% the same.
Think of it like genetics. Chimps share 99% of the same genetics as humans.
I wonder which is the chimp? 