it's not. it's just a restatement of the other arguments, and the response is the same as it is with the other arguments.
first, let's acknowledge that it's a desperate reaction. what it states is that you can't win the argument that hillary is substantively better than trump, so you're just not making it. instead, you're essentially changing the topic. so, it's a red herring. when you say hillary isn't better than trump, that doesn't somehow not apply to the supreme court nominees.
what would hillary's supreme court nominees look like? they'd be pretty shitty, no doubt - designed to protect corporate power and uphold the status quo. and, remember: hillary supports a constitutional amendment to limit abortion rights. she only came out in favour of gay marriage after the court ruling, and only because of the court ruling. she is a conservative, so you should expect her to appoint conservatives. the best case is the status quo; a realistic expectation is actually a shift to the right, as she'll no doubt replace the democrats that resign with justices that are more conservative.
so, like everything else about hillary, you should expect her supreme court nominations to be horrendous. disastrous, even. but, they'll be chosen in such a way as to not rock boats. you won't realize the shit has hit the fan until it does, if you do at all. so, we get this continuing shift to the right without anybody noticing.
what about trump? well, you'd expect little subtlety in his picks, although i don't think you should take him seriously on the abortion thing. but, let's say you do. let's say he literally appoints judge judy. and, let's say he somehow gets her confirmed. people are going to riot.
so, what do you want? do you want eight more years of the status quo, where they're fucking everybody over and nobody reacts? or do you want some serious pushback?