Even if it's scientifically imperfect, it's excusable. The crew needed to enter Big Ben to advance the plot by [rot13:rkcrevrapvat gur arhebybtvpny rssrpgf bs gur fpenzoyref svefgunaq].
Remember I read Echopraxia first (but after the domestification of vampires) and Blindsight second. Echopraxia was such an astonishing mess of badly thought out things that when I started to read Blindsight I had very low energy to continue reading.
The Blindsight started with firefall, that is a 65K things that suddenly appeared and photographed the Earth while burning in atmosphere.
Do you know that current 1sqkm radio telescopes produce data that can't be processed at real time in any cluster environment in use at 2015-2016? They scan skies at precision I just cannot express in words, let's try math.
https://www.skatelescope.org/uploaded/2950_31734_2007_IAU_Ta...
"...with a resolution of few micro-angular-seconds..."
sin(5/57/60/60/1000000) equals to 2.4366472e-11. It is sine of roughly 5 micro angular seconds (1 radian is about 57 degrees). 1/sin(5/57/60/60/1000000) is roughly equal to distance where current SKA can distinguish 1 meter radio-emitting object and it equals to about 41 million kilometers - a fourth of the distance between Sun and Earth.
These Firefall objects just won't be "unnoticeable until their entry to the atmosphere" in the state of the art sky scaling systems of Blindsight's time.
Almost everything in Watts' works just don't add up. I cannot break the wall of disbelief because of that, sorry. What others see as a minor forgivable thing I see as another transgression against laws of physics, rate of progress, etc, etc.
The prose by Watts is so much against my life, hobby, sports and work experience that at some point of time I started read his work as something like this: "some uninteresting rant, fuck you, Serguey, some more pseudointellectual babble". I even started to re-research what I knew because I looked to myself so very wrong with what I considered correct and right. This is quite an achievement on Watts behalf.
And no, I cannot imagine how Watts would be able to satisfy me with the necessity for humans to enter that alien ship. In my opinion, it does not follow because of so many things before.
There probably is no such thing as truly hard sci-fi, as all speculative stories involves handwaving the details, but you seem to be expecting a level of hardness that you won't find in Watts work, or in most fiction.
The "hard science fiction", as I learned being young adult, must present as less fictional hypotheses as possible, the minimum is none and reasonable requirement is one per short story or short novel. Watts keeps providing assumptions at the rate of one per ten pages, to exaggerate a bit.
I do not share your cultural background and 1) know nothing about Crichton and 2) do not love Lovecraft. But I remember reading translation of Martian Chronicles by Bradbury and he succeed with body horror in my opinion, to the point that I profoundly dislike his work up to this day. He wrote hard sci fi (without quotes - single assumption per short story) and to great success.
Again, I consider Watts a bad author with more or less interesting ideas - I keep arguing about them with others and myself. But I will not consume any new piece of his work because, in my opinion, they are very badly executed.