I think you misinterpret Boeing's motives in the complaint against Bombardier. Boeing is not concerned about Bombardier building a larger seat jet but with Bombardier offering its CS300 series which is in direct competition with Boeing's new 737 MAX 7 series. The CS300 seats 130 people and the MAX 7 starts at 138 seats. If Boeing's allegations of government subsidies and dumping below cost are true, then Boeing has a lot to complain about and to be concerned about. The MAX 7 only received FAA certification earlier this year.With the recent orders coming in from the ME, I guess Boeing won't be too concerned with losing 18 SHs. Their intimidation of Bombardier really isn't about the C-Series and the 737 as the competition crossover is minimal, it is a warning shot not to go above the 160 seat threshold. I think they also realize that the F-35 progress is advancing to the point where the SH can't win the final fast jet competition later on. Even junior realizes this which is why the interim purchase was conceived as a face-saving measure.
That aside, I think Canada's threat to cancel the SH deal in retaliation against Boeing's complaint, while being applauded by jingoists, is really quite absurd and the Canadian Press's attempt to make it look like the threat of canceling the deal has struck fear into Boeing's heart is equally absurd. Boeing's lifeblood is its commercial airliner business and the SH deal is Lilliputian in comparison. Of course, Boeing defense is making mollifying noises but Boeing senior management knows where its bread is buttered and that the SH deal is nothing compared to its 737 business. Boeing would not mind losing the SH deal if they were to win their complaint against Bombardier.