Spaniards did not close the passage with a boom does not appear.
Probably they were glad to be quit of Morgan on any terms.

A great Spanish fleet he routed by the ingenious employment of a
fire-ship. In a later expedition a strong place was taken by a
curious accident. One of the buccaneers was shot through the body
with an arrow. He drew it out, wrapped it in cotton, fired it from
his musket, and so set light to a roof and burned the town.

His raid on Panama was extraordinary for the endurance of his men.
For days they lived on the leather of bottles and belts. "Some, who
were never out of their mothers' kitchens, may ask how these pirates
could eat and digest these pieces of leather, so hard and dry? Whom
I answer--that could they once experience what hunger, or rather
famine is, they would find the way, as the pirates did." It was at
the close of this march that the Indians drove wild bulls among
them; but they cared very little for these new allies of the
Spaniards: beef, in any form, was only too welcome.

Morgan burned the fair cedar houses of Panama, but lost the plate
ship with all the gold and silver out of the churches. How he
tortured a poor wretch who chanced to wear a pair of taffety
trousers belonging to his master, with a small silver key hanging
out, it is better not to repeat. The men only got two hundred
pieces-of-eight each, after all their toil, for their Welshman was
indeed a thief, and bilked his crews, no less than he plundered the
Spaniards, without remorse. Finally, he sneaked away from the fleet
with a ship or two; and it is to be feared that Captain Morgan made
rather a good thing by dint of his incredible cruelty and villainy.