Liberty is sort if right, fewer F1 teams are good for them in general.
With most other sports, more teams means more games, which means more fans, more money etc. If you add 2, 5, 100 teams to F1, you still have 22 races, which means the same number of fans, and the same amount of money. Except instead of splitting the 'team' part of the pie into 10, now you're at 12, 15, 110. Everyone gets less, and you get a lot more grumbling about 'have' and 'have not' teams.
Of course, that's the short term look. When you're a corporation with shareholders who care about the next quarter, not the next 50 years, it's hard to look past that. Anyone who has followed F1 long enough knows that teams rise and fall (and hopefully rise again), and that's what makes the sport interesting. McLaren, Lotus, Ferrari, Mercedes, they're all big names in the auto world, they all started out as small racing teams with innovative approaches to the sport. Could you imaging trying to squeeze one of them out now?
Or what about the Force India experiment, trying to bring motor racing to India? It may not have worked, but you won't grow the sport sticking to British and Italian teams. Alfa Romeo has put in a lot of years as a Swiss outsider, the sport needs more 'outsiders' in Spain or Russia (even if they're still based from British factories)
I'd love to see F1 grow the fan base, that means having more representation around the world. That means more teams. THAT'S when the pies grow, that's when Ferrari makes more money in a 15 team sport than they did in a 10 team sport, where Liberty's shareholders make an extra dime per dividend.