I don't think so. I think Loomis truly believes that DA can be the coach we need to win a lot of games. Loomis is patient in that way. I disagree with him, but I think he is keeping DA because he thinks he can be the guy, not because he thinks he is somehow saving money by not paying Harbaugh or another coach.
Frankly, if not interviewing Harbaugh means you don't want to win, that would mean that probably around 27 other teams don't want to win too since there are probably only about 4 great coaches in the NFL right now and the Charger hired Harbaugh.
Anyway, the only real pressure fans have is to not buy tickets and not buy merchandise. Of course the problem is that if we don't buy tickets long enough, the team is going to move.