yes it's his npub.
ots is simply a cryographic approach to proof something happened after a specific time.
for example when an event published.
someone did an ots for ross post and nostr:nprofile1qqsve2jcud7fnjzmchn4gq52wx9agey9uhfukv69dy0v4wpuw4w53nqpz9mhxue69uhkummnw3ezuamfdejj7ysp3f3 is wondering is that him or someone else.
afaik, ross is using primal and primal won't let him to do it. so, i believe its someone else probably using amey. not hard to find out who is him.
i hope it be clear for you.