Theory time.
a.) Captain was coerced against his will into blocking the canal by derps and was trying to send a message that the derps wouldn't catch, but that someone later would.
b.) Captain knew there was illicit cargo (human, drugs, weapons, NUKES) and sent the message on his own recognizance (I know, wrong word, but I like it) and then stranded the ship to put an end to the evilness all on his lonesome.
And blocked Suez canals get attention.
I can see no reason, other than blowing up the canal, for him to purposefully block the canal of Nukes were onboard and he knew it.
So, yea. I'm gonna hang out in the ballpark of these theories until proven otherwise.
\Of course, if its nukes, we may never know.
here’s a what-if for you.
Suppose that some errant cargo (human, drugs, weapons, NUKES) was not on this ship but another.
Suppose the operator of this particular ship was a white hat and chose to block the canal in an effort to prevent another Wessel from reaching it destination, or to allow time for the navel forces to set up an interception operation for said Wessel. (reaching my inner Chekov here)
Either way, a blocked Suez Canal gets a lot of attention. :)
There are no coincidences - perhaps this was a message to Evergreen herself, that whatever plans she had were blocked.