That is a way narrower definition of competition than typically gets used in these examinations. Any of the Big 3+WN could turn on a nonstop tomorrow and they all can offer a single connection today.

AS right now routinely funnels SEA O/D traffic through a CA connection to balance demand so it’s not like connecting flights are so undesirable that they’re not legitimate competition.

HA is less than 2% of the available seat miles for US-based airlines and FTC would get laughed out of court if they tried to claim that the distant fifth among US airlines was going to hurt competition when their combined size is still going to keep them a distant fifth, with roughly half the ASMs of number four.