What was this problem again?
I'm a bit unclear about what was hacked. Does the TikTok app receive SMS messages, or, is this about a hacker sending malicious SMS with a link to a handset malware web site, with TikTok as the apparent (and actual) SMS sender?
And, can't hackers send evil SMSes of their own anyway? So the only difference is that they are falsely hiding behind TikTok's reputation for respectable communiation. And are not paying.