That's a statement more about how the developers feel or want to feel. The reality is that the games are, in fact, going to be in competition with each other because they'll both be for sale in the same market and can't be paid for with the same dollars nor played at the same time. Competition is inevitable and no feel-good statements are going to change that. That competition may not be hostile and it may not be aimed at driving competitors from the market, but they will be in competition.
By that logic, Rice Crispies are in competition with dish soap. They're for sale in the same market, and cannot be paid for with the same dollars - and time you spend washing dishes is time you can't spend eating cereal! This is a very simplistic view of competition.
I would suggest, instead, that two things are in competition when purchasing one greatly reduces your likelihood of purchasing the other
and that lack of purchase impacts progress to the company's goals.
As an example - imagine there are two concerts in town on the same night (let's say, Aerosmith and Postmodern Jukebox). There's significant overlap in their fans. If you buy a Jukebox ticket, you aren't going to the Aerosmith concert. Does Aerosmith care? They're going to sell out whether or not they're sell the ticket to you. And Postmodern Jukebox is trying to sell out a much, much smaller venue - if they can do that, no matter what Aerosmith does, there's no issue. So, in this case, the overall market is large enough for everyone to meet their goals, and there is no effective competition.
If, as has been suggested, the Dungeons and Dragons brand, as a whole, has bigger fish to fry than the tabletop RPG business, then maybe they really aren't in competition. So long as they get enough sales to keep the brand name cemented so that they can sell other products and media, they really may not care - the brand may really be aiming for revenue from a different market.
To make up examples out of thin air - If D&D had one single successful blockbuster movie, sales of the RPG would mean zilch. Or, if they got a real hit mobile app game, again, the tabletop RPG sales would not be an issue.
As a more likely scenario - Let us face it, Pathfinder's a complicated game. WotC may be positioning themselves to be the "entry game" for the market again (*free* Basic!). They may be intending to grow new market for themselves in a way that Pathfinder and other games just *can't*. If they can meet their goals in this manner, then they are not in competition with Pathfinder.