What's bad about this is the use of the language of the anti-harrassment movement (are you familiar with the #TimesUp hashtag?) to express political differences.
I don't know that much about Feinstein, frankly. From what I do know I'm probably more inclined to support her opponent. And to be clear her opponent's supporters are not uniform in this tactic, but it's an ugly one. Feinstein is not someone who committed sexual assault or harassment and is now being justifiably outed on those grounds*. Nor is she comparable to one. The reason this is bad is not the injury to Feinstein, it's the way in which #MeToo has been co-opted and trivialized. IMO, #MeToo is an area where there's a great deal of inadequacy on the left, and this seems like an example of that.
*I mean, maybe she is --- but AFAIK, this is largely about her "militarism" and deference to the security state; at least, if Glenn Greenwald's characterization is reliable. It isn't always.