Kant is not saying here that space and time vanish as soon as the subject vanishes. (…) Look again. "space and time exist only in the subject as modes of perception. Because to Kant, even space and time are only appearances to us — L'éléphant
Given minor differences in translations, yes, he is, and no, they are not. Mode of perception is not perception, and neither space nor time is ever an appearance, but only that which is
in space and time, is.
“….It will first be necessary to explain as distinctly as possible our opinion in regard to the fundamental constitution of sensible cognition in general, in order to preclude all misinterpretation of it.
We have therefore wanted to say that all our intuition is nothing but the representation of appearance; that the things that we intuit are not in themselves what we intuit them to be, nor are their relations so constituted in themselves as they appear to us; and that if we remove our own subject or even only the subjective constitution of the senses in general, then all the constitution, all relations of objects in space and time,
indeed space and time themselves would disappear, and as appearances they cannot exist in themselves, but only in us. What may be the case with objects in themselves and abstracted from all this receptivity of our sensibility remains entirely unknown to us. We are acquainted with nothing except our way of perceiving them, which is peculiar to us, and which therefore does not necessarily pertain to every being, though to be sure it pertains to every human being. We are con- cerned solely with this. Space and time are its pure forms, sensation in general its matter. We can cognize only the former a priori, i.e., prior to all actual perception, and they are therefore called pure intuition; the latter, however, is that in our cognition that is responsible for it being called a posteriori cognition, i.e., empirical intuition. The former adheres to our sensibility absolutely necessarily, whatever sort of sensations we may have; the latter can be very different
for different subjects. Even if we could bring this intuition of ours to the highest degree of distinctness we would not thereby come any closer to the constitution of objects in themselves. For in any case we would still completely cognize only our own way of intuiting, i.e., our sensibility, and this always only under the conditions originally depending on the subject, space and time; what the objects may be in themselves would still never be known through the most enlightened cognition of their appearance, which is alone given to us….”
(Guyer/Wood, 1988, emphasis mine)
(Kemp Smith, 1929 is clearer, but older, so….)
Cognition in general is the process
writ large, for which perception is merely the initial occasion;
To take away the nature and relations of objects is not to take away the objects;
The mode of perception merely indicates particular affected sense(s);
“ and as appearances they cannot exist in themselves” only means the constitution and relations of objects of appearance;
To be real is to appear to a sense as given matter, to appear to a sense is to affect it, to affect it is to cause a sensation,
…..there is no sensation of space or time, neither affect a sense, neither appears to senses in general, neither are appearances, neither are real as given matter;
The mode of perception is not the same as the mode of intuition, the former determined by physiology, the latter determined by the type of sensation such physiology provides;
Space and time merely represent the irreducible commonality of every sensation, without regard to its physiological cause;
Absent this particular,
albeit speculative, form of human intelligence, there is no need for irreducible commonalities, thus the absence of space and time is given from the absence of the human subjective condition.