I don't think it's Girona that is blocking Atletico Madrid and Barcelona, but Atletico Madrid and Barcelona's performance this season is quite bad so they can't put pressure on Real Madrid in the competition for the title this season, while Girona only makes a surprise without being able to put pressure/compete in the race. This season's La Liga title with Real Madrid because in terms of strength they are not capable or equal to Real Madrid.
We must admit that the performance of Barcelona and Atletico Madrid is rather badly during this season. The main problem of these teams are they failed to build a strong team with proper players. It makes sense for Barcelona, they have financial crisis. Meanwhile Atletico Madrid, they lose their mentality in the last few seasons. Simeone failed to rebuild a strong defense of Atletico Madrid. Having the bad situation on these teams, we have Girona who can perform very impressive since the early of the season. They could compete with Real Madrid for the 1st place although they don't have many popular players. This is a coincidence, Girona performed impressive when Atletico Madrid and Barcelona are underperformance.
Finishing in 2nd or 3rd position is the same because a team that cannot win the title will only focus on being able to finish in the top 4 positions so that they can get a ticket to the Champions League next season, but it all comes back to the prestige of being able to finish in the best position, and every team has motivation for it.
I think it is a bit different when you could finish as a runner-up (second place). It is a bit prestigious status but it won't mean a lot because all the teams in the position 2-4 will be in UCL for the next season. I think Barcelona and Atletico Madrid won't care if they finish in 2, 3, or 4. But for Girona, I'm sure they will try all out to finish as a runner-up. They want to show all people that they are the second strongest team in La Liga nowadays.