I would have agreed were it not for the Stroll lead consortium saving Aston Martin. He now has a business reason for the F1 team to exists and be successful. The F1 adventure has to be a positive marketing opportunity to sell cars. If they are near the back of the grid this does not reflect well on the road cars. So if Lance is consistently and comprehensively outmatched by Vettel (and surely he will be) and it's received this is having a negative impact on the brand he might get pushed out
Only if F1 results have a direct effect on road car sales. Which is a debatable point. However, that isn't what Aston Martin marketing is about anyway - Aston Martin sells expensive cars to people with a lot of money, who generally have a bit of a status. Aston Martin merely existing on the F1 grid allows them to invite people of status (high end businessmen, footballers, celebs) to F1 events, and wine and dine them with expensive food and hospitality in the middle of Monaco. If the Racing Point Aston Martin doesn't win, nobody remembers. The clients remember being wined and dined in a yacht in Monaco, or the hotel in Abu Dhabi.
Whilst it was more important for the likes of Toyota, BMW, Honda and even Mercedes to win races to sell cars, it is less so for Aston Martin. They sell it on status.
Evidence of this is seen in WEC, where Aston Martin have been around since the start. They've been racing their GT1, GT2 and GTE cars in various classes at Le Mans and surrounding series for almost 20 years now. Even when it was just Corvette vs Aston Martin, they were still there. Even when it was clear the Aston was the complete dog of the class with no chance of winning they were still there. They even funded entire Aston Martin support events for the Le Mans 24 Hours - not because it was good marketing for the public, but because it allowed them additional paddock space to bring along more hospitality and bring in wealthy people who'll buy their cars. And that's why they've stuck around in WEC, even when struggling - whilst Ford has packed their bags and left, because they won't be selling road cars off of a project not winning. Aston even fund Am entries to various ACO events which have zero chance of winning - but allows them more hospitality to bring in potential car buyers. If had $200,000 to spend on a car, and Aston invited me to a race, there's significantly more chance of me buying an Aston. And then I tell my rich footballer and businessmen mates about how amazing my car is, and they buy one next time round too.
As long as Racing Point isn't last, it's a marketing success for the Aston Martin brand due to who their client base is. As long as the team isn't embarrassing it's fine - it isn't about the result, it's about giving the rich people the F1 experience. Which Aston Martin will do spectacularly (because they're bloody good at it at Le Mans).