optimal play: I think you're right.
Although Chessgames lists it as a simul, not necessarily a blindfold, according to contemporary press reports it was one of "several slight skirmishes" aka casual games, they played on or about the 9th of February 1885 in Melbourne just prior to his departure for Sydney.
<<<<<CHESS IN MELBOURNE.>
Mr. Blackburne, before his departure for Sydney, played several slight skirmishes with Mr. Fisher. The following is one played at Scott's on the 9th inst.->
NOTES BY MR. BLACKBURNE.>
<(a) 4... P to K Kt 3 <4...g6>
This defence is given as the best by *Stamma.>
<(b) 6. Kt to Q 5 <6.Nd5>
The Knight is useless on Q 5 <d5>, and therefore, a loss of valuable time in placing it there. B to Q 2 <Bd2> preparatory to castling on the Queen's side would have been preferable.>
<(c) 14. Q takes Q <14.Qxe7>
Black has now the better position, and White is almost compelled to exchange Queens ; had he played K to B 2 <Kf2> the reply would have been Q to B 3 <Qf6> with an overwhelming attack.>
<(d) 21. P to K R 4 <21.h4>
The only move to prevent the advance of K Kt P <g-file pawn>.>
<(e) 21... R to K sq <21...Re8>
It would, perhaps, have been more prudent to have first moved P to K R 4 <h5>.>
<(f) 28. R to B 7 <28.Rf7>
Mere desperation, but there is nothing else for him ; had he played R to R 6 <Rh6>, Black wins easily by B to K 5 <Be4>.>
Australasian (Melbourne, Vic.), Saturday 21 February 1885, page 2>
Blackburne actually had a high opinion of C. M. Fisher, comparing he and Andrew Burns as equal to the best amateurs in England, which is high praise considering that all chess players in Australia at that time were amateur.
Also, just in case you have not already done so, I submitted a correction slip to amend the description from a simul exhibition to a casual game.