No, I don't think Peter Van Loan's finger-wagging merits the response it received - as talk of nearly every other issue ground to a halt yesterday in response to an incident of little substantive importance. But I do think it's worth making a couple of points as to how we should respond to it - and how best to minimize the effect of similar stunts in the future.
To start with, there's always a danger in responding to behaviour like Van Loan's as primarily an attack on one's own party. Again, that's where the Libs look to me to have lost the plot on the Cons' past contempt of Parliament: they took as a given that voters would see "they're being mean to us!" as worthy of outrage which would then operate in their favour, and proved wrong on at least the latter count. (The NDP responded somewhat better by pointing to a need for more respect for Parliament generally - but even that allowed the Cons' stunt to deflect from more substantive issues.)
But it's also worth noting how the outsized visibility of party leaders might play into incidents like yesterday's - and how a party might seek to counter that effect.
While I'll presume Van Loan's attack on the NDP was spontaneous absent evidence to the contrary, it's far from unheard-of for opponents to try to set up negative photo-ops for their competitors' leaders. And that makes for a rational if cynical calculation in a political culture where those leaders are seen as the sole faces and decision-makers for their parties.
Indeed, given the incentives at play I'm surprised the Cons don't (so far as I know) have staffers or volunteers dedicated solely to harassing competing leaders at every opportunity - with the primary goal of luring them into gaffes, and the secondary "benefit" of making it difficult to think and act without interruption. (And given the asymmetry in security and planning capacity between the government apparatus and an opposition party, it would be rather difficult for anybody to respond in kind.)
In that vein, even a calculated effort to try to provoke opposition leaders in the House of Commons might make sense as a Con public relations exercise - both by diminishing the institution to the advantage of an anti-government party, and by attaching some negative impression to an opposition leader (while the balance goes to some less-recognized government member rather than Stephen Harper personally).
Now, one way around such traps is for an opposition leader to be a saint who avoids responding to any provocation whatsoever, and develops enough positive impressions to overcome the negativity imposed by the governing party.
But while that might seem like the easiest option for an individual leader to control, there's another path available: working on rejecting the leader-centred framework which both favours an incumbent who can afford to stay above the fray, and creates incentives favouring attacks on one's own leader. Instead, better to emphasize that the actions of MPs and staffers on all sides reflect an institutional culture - and that votes involve a choice among parties and their respective cultures, not merely the selection of a single leader.
Of course, it'll be no easy task to develop that alternative framework. But success in shifting toward a greater recognition of party brands and cultures will make it far more likely that actions by other Cons besides the heavily-insulated Harper can be tied together as a matter of public impression - which will work wonders in making the case for change.