Your Terms of service appear to be all about Sending messages.

There appears to be nothing that specifically prohibits using a Yahoo account to collect information from Replies to Spam, Phishing, etc.

Add an additional Term of Service to Prohibit using a Yahoo account to RECEIVE REPLIES from SPAM, Phishing emails etc!

I have received several SPAMs that were Sent from a non-Yahoo email provider, but used a Yahoo account as the REPLY Address.

"Customer Care" often dismisses these complaints as " the email in question didn't originate from the Yahoo Mail system"