This account is rare, all the digits of the id are the same for example: STEAM_0:1:1111. So yes it is worth more than the normal 4 digit of 70-120$. The price is hard to say because you haven't seen an account like this being sold before. It is up to the buyer and seller, so please stop arguing about the price.
For safety reasons it is entirely up to the owner who he decide to share the exact id of the account.
https://i.gyazo.com/2d270094b68ea9a7e6d86c090d95298c.png
Regarding the account being empty or not is possible. I have had my own 3 digit emptied by steam support, this deleted all games that was existing on the account. We don't know how support will react, they handle cases differently. I have heard many different speculations with Steam support over the time, so it is a very hard thing to argue about.
Seller is not violating any rules on Sythe as far as I know. Speculations about scam here is not justified, but personally I wouldn't feel safe buying this account (This is just my opinion, old accounts are never really 100% safe).
If the seller wants me to verify that the account is empty he can feel free to do so, it is a quite simple process. I can not remember when I verified it if it was empty or not, it didn't really matter to me.