Can we assume computer be fast enough?

Question

Consider such a question

Take a program P and an integer n, check whether P halts. You may assume that if P halts then P halts in n steps.

and solution 1

(P,n)=>!run(P,timeout=n us).timeout

solution 2

P=>!run(P,timeout=9 us).timeout

where S1 assumes n steps will finish in n us and S2 assume in 9 us.

Do we allow such assumption in code-golf?