Fan interference and a speedy runner

[_Bruno_]

hi,

i need a little help with that. R1, 3-2 count, 1 out.
R1, a pretty fast runner, is going with the pitch becuause he thinks that there are already 2 outs. the ball is hit into deep RF. the Rf leaps and tries to make the catch, but a fan interferes. the speedy R1 is already half way between 3B and home plate.
the umpire rules fan interference ! in his mind the RF would have caught the ball.
but what about R1 ? would you call him out because he would have no chance to get back to 1B in time ?

thanks in advance