As a complete layman, I do wonder why n grows with each subsequent curve, rather than with number of bits. Does this not suggest they were 'searching harder'?
reply>they can be hit randomly with 2^30 tries
replyMore precisely: not very random tries.
unless your guess is that the hypothetical ECC weakness is somehow correlated with the LCG structure, the draws from the LCG are as good as random.
replyIt is possible such a correlation could occur. but it would be much weirder than this being the result of a random search, which would already be very weird.