Toslink has the advantage of providing complete electrical isolation. On the other hand, it is more prone to clock issues, mainly jitter. Which connection will serve you best depends on your requirements and the particulars of your system.
If he elaborated he might have mentioned most DACs which use optical these days have enough jitter rejection to easily negate the nasties like those from the early Toslink iterations. For example, Rob Watts from Chord Electronics weighed in on this topic a couple of years ago in regards to their QuteHD DAC and stated because of their FPGA implementation the sound quality was equal across all inputs.
Your earlier post in this thread is spot-on in my opinion. There is much unnecessary bias against optical and the seeming knee-jerk reaction from audiophiles, as quoted below, sums in perfectly.
The reason I’m going on about all this, is that people like myself, that have been into high end audio during the 80’s and 90’s, have a natural bias against Toslink. The minute someone mentions Toslink to someone like me, a little light in my head goes off. Sometimes I see the word Death light up, and other times I see Bose. There are a lot of people that have this natural bias against Toslink, and to be fair, I’m not sure if its justified. You need to know this because for all I know, they may have Toslink sounding great. Most of us have never given it a chance.
I’m not advocating for Toslink optical BTW, I just believe many audiophiles steer others unnecessarily away from a connection method which may in fact be quite useful (electrical isolation). So, @coree, as usual in our hobby it’s system dependent. Yes, you should consider the quality of the output of your Blu-ray player if you care about good sound, but don’t shy away from using Toslink because many dismiss it out of hand.