User:SOTO/Forum Archive/The Panopticon/@comment-4028641-20151008023030/@comment-6032121-20191119184336
Thinking that this was a "doesn't matter which face" thing would, I think, be speculation.
And if it even is codified policy anywhere (is it? I know covers are a "last resort", but fully-integrated illustrations like this?), the idea of illustrations being secondary sources would surely, only come up if this notion conflicted with anything. And it doesn't really. The Master's past is murky enough that for all we know one of their past incarnations could have looked like Ainley; we know the Master burned through regenerations quickly in their youth, so it should be no wonder that other stories taking place in approximately the same era give him different faces.
The point that this is all viewed through the prism of the Master's storytelling, however, is much more relevant. We can definitely moderate this sentence with "An account the Master once gave of his early life depicted the regeneration who killed the Lord President around the time of the Doctor's departure from Gallifrey as greatly resembling the body the Master later inhabited after possessing and merging with Tremas", or something like that.
All in all this business is only a minor point; it's just yet another example of accounts explicitly showing that some faces of the Master's (Beevers, Ainley) actually do recur throughout their lives, and thus that one cannot simply order the faces chronologically and expect that to coincide with the chronological order of how those stories happen to the Master in-universe.