if Grindr were a homogeneously gay community, this might not be an issue.
Many profile images, (and more each day) have brought me uncomfortably close to vomiting. none of these users are seeking gay men.
If the intent is to discourage people from touching themselves, it has been extremely effective.
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in the context of blocking users for the purpose of maintaining arousal and being able to keep food down, here are my suggestions..

Blocking is a 3-click, slow process that often fails. The failures are code defects stemming from the app’s architecture.. because the app is overloaded
Time and effort required by the user and the burden on the client and server could be cut in half by simply separating trans female (and those seeking them) into a cloned app with its own database.

As it is, I have to look dead center at every disturbing profile photo in order to hide it. (Assuming the block succeeded the first time)

Block should be one-tap, the profile image should immediately go away, the client should verify the block after posting to db, and a temporary text box should inform the user when the block is successful, along with an undo button that fades away over a few seconds.

For blocking stalkers and similar people that keep coming back under another account, it should be part of the profile moderation/reporting feature. This is also an easy mod, not just UI, but also the implementation of an algorithm to identify users by MAC or IP address, location and certain other data