This is an interesting point. In the case of typical restriction enzyme digestion, it is double stranded DNA that is being digested. So in this case the SSBs are presumably binding to the sticky ends after digestion, so there is no competition with the restriction enzyme.
If you are interested in a specific case where you are digesting ssDNA, and have decided to add in single strand binding proteins, the binding strength (rate constants) of the SSB and restriction enzyme would influence how much the enzyme can displace the binding protein.
Here's a paragraph from the NEB/T4 gene 32 page indicating many similar applications involving reverse transcriptases, polymerase etc.
"Recently, it has been shown to improve restriction enzyme digestion
(6), improve the yield and efficiency of reverse transcription (RT)
reactions during RT-PCR (7-9), enhance T4 DNA polymerase activity
(10-11), as well as increase the yield of PCR products (12)."
EDIT: Although the reference (6) cited by NEB does not have any evidence that proves the enhancement of restriction digestion with single strand binding protein 32. This chapter might be helpful? - Kowalczykowski et al., "21 single-stranded DNA binding proteins." The enzymes. Vol. 14. Academic Press, 1981. 373-444.
From their abstract, it looks like the mechanism of enhancement could be through prevention of ssDNA hairpins so that the endunuclease can access it's recognition site (I haven't read the full chapter). Another fact supporting this is that ref(6) mentions that other interacting enzymes can work alongside SSBs only when SSB's are not saturating all the DNA in the in-vitro reaction. In an in-vivo context, the chapter abstract states that intracellular SSBs are sufficiently abundant to saturate all ssDNA intermediates formed inside cells (I presume they are talking about E. coli)
Below is the supporting text from reference (6) mentioned by NEB - bolding is mine, for emphasis : Bittner, M., R. L. Burke, and B. M. Alberts. "Purification of the T4 gene 32 protein free from detectable deoxyribonuclease activities." Journal of Biological Chemistry 254.19 (1979): 9565-9572.
Nuclease Assays-The presence of both exo- and endo- deoxyribonuclease contaminants in the 32 protein fractions has been monitored carefully throughout these purification schemes. The results of exonuclease assays are presented in Table III, and the results of sensitive endonuclease assays are presented in Table IV. Note that, when such assays are designed to detect nuclease activities on single-stranded DNA, it is important to test 32 protein at subsaturating, rather than only at saturating, protein to DNA ratios. Otherwise, an activity which hydrolyzes only free (non-32 protein-com- plexed) single-stranded DNA will escape detection.