chmod 0 /usr/local/bin/gif2tiff (default perms are 0755, if you need to revert it)
Well, someone might be calling it with network input in the middle of a web request handler, for example. Plenty of vulnerabilities get remotely exploited either due to the user having found a way to connect the net into them, or the user being persuaded to run the exploit. The risk with this one shouldn't be terribly high for most people, but it's certainly non-zero and possible for someone to be attacked through it.
That would still result only in gif2tiff crashing and that wouldn't open up any more attack vectors. Denial of service for sure but that wouldn't help the attacker to gain any more surface to attack.