For the same reason that other posters are desperately wanting this to be a burglary.
To spell this out the right (especially Reform) want this to be political so that a) the left can be shown to be the violent un democratic and extremists and b) it helps Farage on his current £5m gift for security investigation/ scandal.
The left want this to be a simple burglary for the opposite of the above reasons.
For sake of clarity the police have not said it was not politically motivated, they have said at this time there is no evidence to suggest it was politically motivated. They are very different views.