Fixing yet another date math error

rocketbot/cogs/crosspostcog.py

 			Storage.set_state_value(message.guild, self.STATE_KEY_SPAM_CONTEXT, spam_lookup)
 		key = f'{message.author.id}'
 		context = spam_lookup.get(key)
-		if context is not None and message.created_at - context.age > max_age:
+		if context is not None and message.created_at.timestamp() - context.age.timestamp() > max_age.total_seconds():
 			context = None
 		if context is None:
 			context = SpamContext(message.author)