That’s the issue.
i_2 is iterating over index mentioned below

model.classifier = Sequential(
(0): Dropout(p=0.5)
(1): Conv2d(512, 2, kernel_size=(1, 1), stride=(1, 1))
(2): ReLU(inplace)
(3): AvgPool2d(kernel_size=13, stride=1, padding=0)
)

Since, classifier has only one Conv2d, that too at index 1, _i > 2 condition is never satisfied.
Please remove _i > 2 from the condition and only check for

isinstance(module, torch.nn.modules.conv.Conv2d)