Is there any way to lock the Apple TV remote?

The only other option is to change Touch surface tracking:

1. Open Settings  on Apple TV. 
2. Go to Remotes and Devices > Touch Surface Tracking.
3. Set Tracking to Fast to make smaller thumb movements move farther on the Apple TV screen. Set Tracking to Slow to reduce tracking sensitivity.

By default it’s on medium so you might want to choose Slow

Control the Touch surface sensitivity on Apple TV - Apple Support

And you can submit feedback to Apple: https://www.apple.com/feedback/appletv.html

To be honest I'm not a huge fan of the Siri remote. What I did was to upgrade to a universal remote that I can use for all my tv related devices. My setup includes:

Apple TV

TV

HT Receiver

DVD Player

etc...

So rather than having several remotes dancing around, I got a universal remote that controls them all. I opted for a Logitech Harmony. You can get them starting at about $50, while not cheap in the long term they are a life save.

If you have an iPhone, you can also use the Remote app on that. Just make sure that you put the remote somewhere safe. It makes reconnecting after a change in the WiFi network much easier.

Your welcome!