r-
Of course you could challenge anybody ... but you do not challenge F- in this case.
To ask "what went wrong with TA 6 months ago?" isn't a challenge of F-, it is the challenge of TA.
If you would like to challenge F- do (in advance, not after the fact) as (e.g.): "Your conclusion is wrong, since TA "says" / suggest x ... y ... z will happen."
To say the fact isn't the same as your projection isn't an intelligent challenge.
Take or leave (or learn TA), but to ask somebody why TA (his prediction purely based on TA) isn't 100% perfect ... well.
Best,
G