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Am I correct?
Yes, you are basically right. Except, that TX mentioned earlier is probably not related to this case since the information in screenshots, particularly the block number and timestamp, doesn't match up. "saxydev"
claims that the transaction was confirmed in block
2813799 (mined about 10 days ago), and the mentioned TX is part of block
2820718 from a few days ago.
I see. But let's suppose we insist on using that TxID as it's what admitted by saxydev to be the valid TxID, and thus, the complete web address as I wrote above, will entering both entries --the address and the TX private key-- brings us a "false positive", i.e. it will says xxx amount of XMR --equals to 90$-- was indeed sent to OP's address while saxydev actually never send it? Or will it says something like, "invalid data, transaction not found"?
If what'll happen is the latter, then the result itself is conclusive enough that saxydev has never send the payment and brings us to the end of this case.
For the record, saxydev never confirmed that TxID. We inferred this from the screenshots provided by c0ldbrewz. (Which are most likely fabricated to mislead the recipient.)
You can never get a "false positive" result. Either he will give a valid
that will validate the transaction, or you will get an error message such as "the transaction cannot be decrypted," depending on the tool used.