The law makes the situations not analogous.
Also, Baker said making cake violated his free exercise rights. Customer was refused on those grounds. Customer said that it was discrimination based upon sexual orientation which was protected under state law. In that case, the lesbian couple had been granted rights above and beyond what the federal laws granted them. In the case of Twitter, they are refusing provide a platform to this woman to express her views because they say she violated the community rules. Best case it is as you say... they don't want different opinions. I don't believe that it is so, but if it is... What is the argument against Twitter being able to censor their community? This isn't a clash of the rights of twitter vs. this woman's rights. Political ideology is not a protected class and thus this woman is left without arguments.
Twitter is free to discriminate against anyone for any reason not protected by law. (religion, race, color, sex, age, disability and vet status) Twitter could decide to ban all people that had an A in the last name if they so desired. Likewise, the baker could, as well had their state not enacted a law giving protected status based upon sexual orientation.