Sam Adams was happy when the British imposed a harsh punishment on Boston in retaliation for the Boston Tea Party.  This is because Adams was a real radical among the patriots of Boston.

Adams really wanted the Americans to rise up against the British.  He did not want peace or a more just form of living under the British.  So, for him, a harsh punishment was better because it was more likely to make people angry at the British and want to rise up against them.

If the British had not been harsh with Boston, people might have thought "oh, British rule isn't so bad" and that would have made things harder for Adams.

Why did the British punishment for the Boston Tea Party please Sam Adams?

In the book Johnny Tremain by Esther Forbes, Sam Adams appears pleased by Britain’s response to the Boston Tea Party.

Although this might appear an unusual response, Sam Adams trusts that this British response will further unite the colonists against the British. Ultimately, he believes that Britain's actions will encourage the colonists’ support of fighting against the British. As Sam Adams reveals:

“I will work for war: the complete freedom of these colonies from any European power. We can have that freedom only by fighting for it.”

Also, as the text reveals:

“The punishment united the often jealous, often indifferent, separate colonies, as the Tea Party itself had not.”

Thus, Sam Adams wants the colonies to be free from all European powers, especially the British authority. Although he recognizes the horrors of war, he adamantly believes that the cost of war is worth the freedom of the colonies.

Consequently, Sam Adams accepts Britain's response to the Boston Tea Party. Although his feelings might appear extreme, other leaders (such as James Otis) seem to offer even more extreme viewpoints. Regardless, his viewpoint illustrates his value of freedom and independence from the British.