Please pretend that because the Republican party IS tainted by vulgar members that there are none in the party not so tainted. If you see a dot of mold on one slice of bread you have to throw the whole loaf in the trash, even if the children are hungry.
Your analogy makes me think of the cartoon about the curate's egg. Interesting that the original meaning of the phrase (an egg that is 'good and bad in parts' is, in fact, just plain bad, and not fit to be served up, the clergyman only puts it the way he does out of politeness) seems to have been almost lost. These days a 'curate's egg' just means a mixture of good and bad.
I suppose it's a matter of judgement as to whether the original meaning or the current one best fits the Republican Party. I think one could argue the _party_ [in the state it is now] is just plain bad, while not thinking everyone in it is so.
https://www.phrases.org.uk/meanings/163300.html