The official policy for those affected by the strikes with respect to TPs and Avios was posted on ba.com, although it appears to have disappeared at present. Here is the wording in full:

"I’m an Executive Club Member due to travel with you over the impacted period, but my flight has been cancelled. The Tier Points earned would have meant that I upgraded to the next Tier. Will you honour these?

If your flight was cancelled as a result of the industrial action, and you were rebooked onto an alternative service operated by British Airways or a oneworld partner airline, you will automatically be credited with the applicable Avios and Tier Points once you have flown the rebooked flight.

If your flight was cancelled as a result of the industrial action, and you were rebooked by British Airways onto an alternative service operated by a non-partner airline, we will award you the Avios and Tier Points for your original cancelled British Airways flight. Please raise a claim online by logging into your Executive Club account and click the option “claim missing Avios on BA” and submit your original British Airways flight details.

In all other cases where you believe you would have upgraded or retained your Tier status had your flight not been affected by the industrial action, please contact your local Executive Club Service Centre who will review cases on an individual basis."