Sure but you shouldn't be connecting as distinct psuedo-identities during the same Tor session (mentioned in the article); if a custom browser size is associated with a one-time-use anonymous session then it shouldn't be a problem except that it leaks information about what window sizes are possible on your system, and your custom resize is very unlikely to be random; probably predictably proportional to your actual screen size.

Hmm, my thinking was that Tor browser would randomly pick a size, but maybe it only has a certain number of options to make sure every user crosses with plenty of other users too? In which case resizing of any sort would make you more unique, just within the session. (I'm no expert on Tor/browser.)

For those with knowledge of how window size affects page layout, is there any technical reason for Tor browser not to fuzz with a random +/- 5 pixels while in a single session (say, on every page load)?

Similar to what the nosleep utility does with jiggling the mouse by an unnoticable +/- a few pixels.

Too easy to average that away.

Could make sense to do so on a session-by-session basis, though.

Randomly picking a size still gives a good chance of being able to track user connections across a single session.