I'm not particularly sure any of his public keys would be exposed. However @op if you have a problem with this, you can PM me or the user I just quoted with the public key.
I said private key not public key. Any one private key + the MPK = whole wallet compromized. There is no reason to believe any of the OP's private keys have been exposed. Just saying that exposing the MPK is not entirely risk free.
Also, if the seed formats are the same and a new wallet is created then an xpub key should be created shouldn't it? Otherwise, the problem op is facing is merely a compatibility issue.
No that's not the case. Electrum maintains backward compatibility with old seed formats. The MPK would be of the old type too.
@Numerous64: You haven't answered the question HCP posed about familiar addresses. Can you bring the address tab into view with ctrl+a and see if any familiar addresses are listed there?
Also please answer the question I posed above regarding sweeping vs. importing.