I think the guiding principles from CEA would suggest that this is a bad idea
"Because we believe that trust, cooperation, and accurate information are essential to doing good, we strive to be honest and trustworthy. More broadly, we strive to follow those rules of good conduct that allow communities (and the people within them) to thrive. We also value the reputation of effective altruism, and recognize that our actions reflect on it. "
I have one big question: were you originally planning to work this summer?
If you had planned to work and now you can't, then please do apply. You're just as eligible as anyone else.
If you had planned to take the summer off, then the honest thing to do is just stick to that plan and not apply for the extra money.