Unless of course he's violating any (or lots of) the exceptions. https://en.wikipedia.org/wiki/United_States_free_speech_exce...
As spotify is not the american government it doesn't really apply here.
In addition even if they were the american government, that would only apply in america, which is in fact, not the entire world.
EDIT: Replying to child comments: The First Amendment only applies to the government; full stop. If a bakery can refuse service to a gay couple, and a restaurant can remove you for not following dress code, any private business can refuse you service. Period. You have freedom of speech and they have freedom of association. Those are both First Amendment rights. The right to refuse business is right there next to the right to spout off at the mouth.
Those freedoms enabled the best and worst behavior and let people make of it as they will. Laws usually concern themselves with the ways people abuse others: fraud, various kinds of violence, theft, breach of contract, etc. Regulations exist for industries where the risk of damage to many people exists: chemical waste disposal, lending laws, food labeling laws. If the industry needs regulation then that's what we should push for. My interpretation has always been that the constitution establishes what basic expectations of freedoms and restrictions we should have, and laws set the boundaries on where my freedom ends and yours begins.
Giving him the platform seems like exactly what Spotify wants to do, and since we all reached the consensus that private corporations are free to do whatever they want with their platforms, I don't understand what the issue is.
Either that or we could just stop being dishonest and admit that we just want to censor people we don't agree with.
And if people start a campaign to tell people to "Delete Spotify", that seems to be in the realm of acceptability too? Just like people are saying "Delete Uber" because they're taking money from that Saudi "Journalist Chopper" Prince.
If the campaign is to get the government to create a law to muzzle Spotify, then there is an issue...